Dispersants and dispersant viscosity index improvers from selectively hydrogenated polymers

ABSTRACT

The invention provides dispersants and dispersant viscosity index improvers which include polymers of conjugated dienes which have been hydrogenated and functionalized. The dispersant substances include compositions including a copolymer of two different conjugated dienes, a copolymer of a p-alkylstyrene and a conjugated diene, or a homopolymer of a conjugated diene. The polymers are selectively hydrogenated to produce polymers which have highly controlled amounts of unsaturation, permitting highly selective functionalization. Also provided are lubricant fluids, such as mineral and synthetic oils, which have been modified in their dispersancy and/or viscometric properties by means of the dispersant substances of the invention. Also provided are methods of modifying the dispersancy and/or viscometric properties of lubricating fluids such as mineral and synthetic lubricating oils. The dispersant substances may also include a carrier fluid to provide dispersant concentrates.

CROSS-REFERENCE TO RELATED APPLICATIONS

The application is a continuation in part of U.S. application Ser. No.08/382,814, filed Feb. 3, 1995, now U.S. Pat. No. 5,545,783, which is adivisional of application Ser. No. 08/179,051 filed Jan. 7, 1994, nowU.S. Pat. No. 5,387,730, which is a divisional of application Ser. No.07/992,341, filed Dec. 17, 1992, and now U.S. Pat. No. 5,288,937, whichis a continuation of application Ser. No. 07/907,959 filed Aug. 6, 1992,and now U.S. Pat. No. 5,210,359, which is a divisional of applicationSer. No. 07/466,135 filed Jan. 16, 1990, and now U.S. Pat. No.5,149,895. The entire contents of application Ser. No. 07/466,135 areincorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to dispersants, dispersants with Viscosity index(VI) improving properties, and dispersant VI improvers fromfunctionalized diene polymers, and methods of their use. Moreparticularly, the invention relates to dispersants, dispersants with VIimproving properties, and dispersant VI improvers from selectivelyhydrogenated copolymers prepared using conjugated dienes. The inventionis additionally directed to dispersants, dispersants with VI improvingproperties, and dispersant VI improvers from chemically modifiedderivatives of the above polymers.

Liquid elastomers are well known and are used in various applications.For example, many functionally terminated polybutadiene liquidelastomers are known. These materials are generally highly unsaturatedand frequently form the base polymer for polyurethane formulations. Thepreparation and application of hydroxy-terminated polybutadiene isdetailed by J. C. Brosse et al. in "Hydroxyl-terminated polymersobtained by free radical polymerization--Synthesis, characterization andapplications," Advances in Polymer Science 81, Springer--Verlag, Berlin,Heidelberg, 1987, pp. 167-220.

Also, liquid polymers possessing acrylate, carboxy- ormercapto-terminals are known. In addition to butadiene, it is known toutilize isoprene as the base monomer for the liquid elastomers. Theliquid elastomers may contain additional monomers, such as styrene oracrylonitrile, for controlling compatibility in blends with polarmaterials, such as epoxy resins.

Also known in the prior art are pure hydrocarbon, non-functionalizedliquid rubbers. These liquid elastomers contain varying degrees ofunsaturation for utilization in vulcanization. Typical of highlyunsaturated liquid elastomers is polybutadiene, e.g., that sold underthe name RICON by Ricon Resins, Inc. A liquid polyisoprene which hasbeen hydrogenated to saturate 90% of its original double bonds ismarketed as LIR-290 by Kuraray Isoprene Chemical Co. Ltd. Still morehighly saturated are liquid butyl rubbers available from Hardman RubberCo., and Trilene, a liquid ethylene-propylene-diene rubber (EPDM)available from Uniroyal Chemical Co. The more highly saturated liquidelastomers exhibit good oxidation and ozone resistance properties.

Falk, Journal of Polymer Science: PART A-1, 9: 2617-23 (1971), theentire contents of which are incorporated herein by reference, disclosesa method of hydrogenating 1,4,-polybutadiene in the presence of1,4-polyisoprene. More particularly, Falk discloses hydrogenation of the1,4-polybutadiene block segment in the block copolymer of1,4-polybutadiene-1,4-polyisoprene-1,4-polybutadiene and in randomcopolymers of butadiene and isoprene, with both polymerized monomershaving predominantly 1,4-microstructure. Hydrogenation is conducted inthe presence of hydrogen and a catalyst made by the reaction oforganoaluminum or lithium compounds with transition metal salts of2-ethylhexanoic acid. Falk, Die Angewandte Chemie, 21 (286): 17-23(1972), the entire contents of which are also incorporated herein byreference, discloses the hydrogenation of 1,4-polybutadiene segments ina block copolymer of1,4-polybutadiene-1,4-polyisoprene-1,4-polybutadiene.

Hoxmeier, Published European Patent Application 88202449.0, filed onNov. 2, 1988, Publication Number 0 315 280, published on May 10, 1989,discloses a method of selectively hydrogenating a polymer made from atleast two different conjugated diolefins. One of the two diolefins ismore substituted in the 2, 3 and/or 4 carbon atoms than the otherdiolefin and produces tri- or tetra-substituted double bond afterpolymerization. The selective hydrogenation is conducted under suchconditions as to hydrogenate the ethylenic unsaturation incorporatedinto the polymer from the lesser substituted conjugated diolefin, whileleaving unsaturated at least a portion of the tri- or tetra-substitutedunsaturation incorporated into the polymer by the more substitutedconjugated diolefin.

Mohajer et al., "Hydrogenated linear block copolymers of butadiene andisoprene: Effects of variation of composition and sequence architectureon properties", Polymer 23: 1523-35 (1982) discloses essentiallycompletely hydrogenated butadiene-isoprene-butadiene (HBIB), HIBI andHBI block copolymers in which butadiene has predominantly1,4-microstructure.

Kuraray K K, Japanese published patent application Number JP-328 729,filed on December 12, 1987, published on Jul. 4, 1989, discloses a resincomposition comprising 70-99% wt. of a polyolefin (preferablypolyethylene or polypropylene) and 1-30% wt. of a copolymer obtained byhydrogenation of at least 50% of unsaturated bond of isoprene/butadienecopolymer.

Ashless dispersants are additives to lubricant fluids such as fuels andlubricating oils which improve the dispersability of the fluids orimprove their viscometric properties. Typically, such dispersants aremodified polymers, having an oleophilic polymer backbone to assure goodsolubility and to maintain particles suspended in the oil, and polarfunctionality to bind or attach to oxidation products and sludge.Dispersants generally have a solubilizing oleophilic (hydrophobic) tailand a polar (hydrophilic) head, forming micelles when actively bound tosludge.

Common dispersants include polyisobutenes which have been modified bythe ene reaction to include functional groups such as succinimides,hydroxyethyl imides, succinate esters/amides, and oxazolines. Otherdispersants include Mannich base derivatives of polybutenes, ethylenepropylene polymers, and acrylic polymers.

Traditionally, dispersants have been polybutenes functionalized at onesite in the molecule via an ene reaction with maleic anhydride followedby imidization with a polyamine. The polybutenes are typically 500-2,000in molecular weight, and due to the polymerization process employed intheir manufacture, have no more than one olefin per polybutene molecule.Accordingly, the number of potential functional groups per chain islimited to about one. Typically, this site is at a terminal portion ofthe molecule. Moreover, it is generally accepted that, in order toobtain beneficial dispersant properties, a molecule must have at leastone functional group per approximately 2,000 molecular weight.Consequently, the molecular weight of traditional polybutene dispersantscannot exceed 2,000 if the desired functionality/hydrocarbon ratio is tobe maintained. In addition, traditional dispersants have had molecularstructures which have limited the placement of functional groups,generally requiring that such groups be placed at the terminal regionsof the molecules.

The polymerization process for the traditional butene polymers has alsogenerated products having an unacceptably wide distribution of molecularweights, i.e., an unacceptably high ratio of weight average molecularweight (M_(w)) to number average molecular weight (M_(n)). Typically,such distributions are M_(w) /M_(n) ≧˜2.5, producing compositions whosedispersant properties are not well defined.

Moreover, functionalization reactions in these polymers have typicallyyielded substantial quantities of undesirable by-products such asinsoluble modified polymers of variant molecular weight.Functionalization reactions can also result in compounds which containundesirable chemical moieties such as chlorine.

U.S. Pat. No. 4,007,121 to Holder et al. describes lubricant additiveswhich include polymers such as ethylene propylene polymers (EPT) havingN-hydrocarbylcarboxamide groups. Such polymers are difficult tohydrogenate in any controllable manner.

European Patent Application No. EP 0 344 021 discloses polymers preparedfrom p-alkylstyrene and isobutylene. This document discloses that thepolymerization proceeds optimally when the amount of diene in thereaction mixture is minimized. No description is provided as to whethersuch compounds would serve as lubricant additives.

U.S. Pat. Nos. 3,868,330 and 4,234,435 to Meinhardt et al. disclosecarboxylic acid acylating agents for modification of lubricant additivesModified polyalkenes are described such as polyisobutene-substitutedsuccinic acylating agents having M_(n) of 1300-5000 and M_(w) /M_(n) of1.5-4. These processes employ chlorination which results in residualchlorine in the polymer, creating an environmental hazard.

Heretofore, the art has failed to produce dispersants and dispersant VIimprovers having selective and controllable amounts of polarfunctionality in their polymeric structure. Thus, the art has failed toprovide any means of developing dispersants and dispersant VI improvershaving higher molecular weights and/or higher amounts offunctionalization per molecule. The art has also failed to providedispersant polymers having desirably narrow molecular weightdistributions to avoid the presence of by-products which degradedispersant performance. The art has also failed to provide dispersantand VI improving compositions which exhibit good thermal stability.

Accordingly, it is a purpose of this invention to provide dispersantsand dispersant VI improvers having polymeric structures which permithighly selective control of the degree of unsaturation and consequentfunctionalization. Unique materials can also be obtained by chemicalmodification of the polymers of this invention since the polymers can beselectively modified at controllable sites, such as at random sites orat the terminal ends of the molecules.

It is an additional purpose of this invention to provide a method forthe production of dispersants and dispersant VI improvers from polymershaving controlled amounts of unsaturation incorporated randomly in anotherwise saturated backbone. In contrast to EPDM-based dispersants, thelevel of unsaturation can be inexpensively and easily controlled, e.g.,from 1% to 50%, to provide a wide variation in functionalizability.

It is a further purpose of the invention to provide dispersant and VIimproving polymers having narrow molecular weight distributions and aconcomitant lack of undesirable by-products, thereby providing moreprecisely tailored dispersant and/or VI improving properties.

SUMMARY OF THE INVENTION

The invention provides dispersant and dispersant Viscosity index (VI)improvers which include polymers of conjugated dienes which have beenhydrogenated and subsequently chemically modified. The dispersancy andVI improving properties of the compositions of the invention may becontrolled by controlling the size of the polymers and the extent anddistribution of their functionalization. Accordingly, these substancesare termed throughout "dispersant substances".

In one embodiment of the invention, there is provided a dispersantsubstance for modifying the dispersancy or viscometric properties of alubricant fluid, in which the dispersant substance includes a copolymerof two different conjugated dienes. In this case, the first conjugateddiene includes at least one relatively more substituted conjugated dienehaving at least five carbon atoms and the formula: ##STR1## wherein R¹-R⁶ are each hydrogen or a hydrocarbyl group, provided that at least oneof R¹ -R⁶ is a hydrocarbyl group, and also provided that, afterpolymerization, the unsaturation of the polymerized conjugated diene offormula (1) has the formula: ##STR2## wherein R^(I), R^(II), R^(III) andR^(IV) are each hydrogen or a hydrocarbyl group, provided that eitherboth R^(I) and R^(II) are hydrocarbyl groups or both R^(III) and R^(IV)are hydrocarbyl groups.

The second conjugated diene in the dispersant substances of thisembodiment includes at least one relatively less substituted conjugateddiene which is different from the first conjugated diene and has atleast four carbon atoms and the formula: ##STR3## wherein R⁷ -R¹² areeach hydrogen or a hydrocarbyl group, provided that, afterpolymerization, the unsaturation of the polymerized conjugated diene offormula (3) has the formula: ##STR4## wherein R^(V), R^(VI), R^(VII) andR^(VIII) are each hydrogen or a hydrocarbyl group, provided that one ofR^(V) or R^(VI) is hydrogen, one of R^(VII) or R^(VIII) is hydrogen, andat least one of R^(V), R^(VI), R^(VII) and R^(VIII) is a hydrocarbylgroup.

Following polymerization the diene copolymer is preferablyfunctionalized by a method which includes selectively hydrogenating thecopolymer to provide a selectively hydrogenated copolymer, followed byfunctionalizing the selectively hydrogenated copolymer to provide afunctionalized copolymer having at least one polar functional group.

In a preferred embodiment, the dispersant substance includes a polymerin which the first and second conjugated dienes are polymerized as ablock copolymer including at least two alternating blocks:

    (I).sub.x -(B).sub.y or (B).sub.y -(I).sub.x,

In this case, the block (I) includes at least one polymerized conjugateddiene of formula (1), while the block (B) includes at least onepolymerized conjugated diene of formula (3). In addition, x is thenumber of polymerized monomer units in block (I) and is at least 1, andy is the number of polymerized monomer units in block (B) and is atleast 25. It should be understood throughout that x and y are definedrelative to blocks in a linear block copolymer or blocks in an arm orsegment of a branched or star-branched copolymer in which the arm orsegment has substantially linear structure.

Preferably, in the block copolymers of this embodiment, x is from about1 to about 600, and y is from about 30 to about 4,000, more preferably xis from about 1 to about 350, and y is from about 30 to about 2,800.While larger values for x and y are generally related to largermolecular weights, polymers which have multiple blocks and star-branchedpolymers typically will have molecular weights which are not wellrepresented in the values of x and y for each block.

Alternatively, the dispersant substance includes the first and secondconjugated dienes polymerized as a random copolymer. The dispersantsubstance may include the first and second conjugated dienes polymerizedas a branched or star-branched copolymer.

The copolymers useful according to this embodiment typically have amolecular weight of at least about 2,000. Preferably, the molecularweight of these polymers is from about 2,000 to about 1,000,000, morepreferably from about 5,000 to about 500,000.

The molecular weight of a polymer of the invention is generallyassociated with the physical properties it exhibits when employed as adispersant or dispersant VI improver. Typically, polymers having lowermolecular weights are employed as dispersants, while VI-improvingproperties and relative thickening power are associated with polymershaving higher molecular weights and correspondingly greater viscosity.For purposes of discussion, polymers of the invention having molecularweights in the range of from about 2,000 to about 20,000 may beclassified as dispersants, polymers having molecular weights of fromabout 20,000 to about 50,000 may be classified as dispersants withVI-improving properties, and polymers having molecular weights of about50,000 or more may be classified as dispersant VI improvers.

In the dispersant substances of the invention, the copolymer ispreferably selectively hydrogenated. It is preferred that theunsaturation of formula (4) be substantially completely hydrogenated,thereby retaining substantially none of the original unsaturation ofthis type, while the unsaturation of formula (2) is substantiallyretained (i.e., the residual unsaturation after hydrogenation), in atleast an amount which is sufficient to permit functionalization of thecopolymer.

After the hydrogenation reaction, the Iodine Number for the residualunsaturation of formula (2) is generally from about 50% to about 100% ofthe Iodine Number prior to the hydrogenation reaction. More preferably,after hydrogenation, the Iodine Number for the residual unsaturation offormula (2) is about 100% of the Iodine Number prior to thehydrogenation reaction.

After the hydrogenation reaction, the Iodine Number for the residualunsaturation of formula (4) is from about 0% to about 10% of the IodineNumber prior to the hydrogenation reaction. More preferably, after thehydrogenation reaction, the Iodine Number for the residual unsaturationof formula (4) is from about 0% to about 0.5% of the Iodine Number priorto the hydrogenation reaction. Most preferably, after the hydrogenationreaction, the Iodine Number for the residual unsaturation of formula (4)is from about 0% to about 0.2% of the Iodine Number prior to thehydrogenation reaction.

The conjugated diene of formula (1) preferably includes a conjugateddiene such as isoprene, 2,3-dimethyl-butadiene, 2-methyl-1,3-pentadiene,myrcene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene,2-phenyl-1,3-butadiene, 2-phenyl-1,3-pentadiene, 3-phenyl-1,3pentadiene, 2,3-dimethyl-1,3-pentadiene, 2-hexyl-1,3-butadiene,3-methyl-1,3-hexadiene, 2-benzyl-1,3-butadiene, 2-p-tolyl-1,3-butadiene,or mixtures thereof. More preferably, the conjugated diene of formula(1) includes isoprene, myrcene, 2,3-dimethyl-butadiene or2-methyl-1,3-pentadiene. Still more preferably, the conjugated diene offormula (1) includes isoprene.

Preferably, the conjugated diene of formula (3) includes 1,3-butadiene,1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 2,4-heptadiene,1,3-octadiene, 2,4-octadiene, 3,5-octadiene, 1,3-nonadiene,2,4-nonadiene, 3,5-nonadiene, 1,3-decadiene, 2,4-decadiene,3,5-decadiene, or mixtures thereof. More preferably, the conjugateddiene of formula (3) includes 1,3-butadiene, 1,3-pentadiene, or1,3-hexadiene. Still more preferably, the conjugated diene of formula(3) includes 1,3-butadiene.

Generally, when the conjugated diene includes substantial amounts of1,3-butadiene, the polymerized butadiene includes a mixture of 1,4- and1,2-units. The preferred structures contain at least about 25% of the1,2-units. More preferably, the structures contain from about 30% toabout 90% of the 1,2-subunits. Most preferably, the structures containfrom about 45% to about 65% of the 1,2-units.

To provide dispersancy, the selectviely hydrogenated polymer ischemically modified of "functionalized" to provide a polymer having atleast one polar functional group, such as, but not limited to, halogen,epoxy, hydroxy, amino, nitrilo, mercapto, imido, carboxy, and sulfonicacid groups of combinations thereof. The functionalized polymers can befurther modified to give a more desired type of functionality.

In a preferred case, the selectively hydrogenated polymer is chemicallymodified by a method which includes: reacting the selectivelyhydrogenated polymer with an unsaturated carboxyilic acid (or derivativethereof, such as maleic anhydride) to provide an acylated polymer, andthen reacting the acylated polymer with a monoamine, a polyamine or acombination thereof.

In another preferred embodiment, the invention provides dispersantsubstances based upon a copolymer of at least one ring-substitutedstyrene and at least one conjugated diene. Preferably, thering-substituted styrene has at least one benzylic hydrogen and theformula: ##STR5## wherein n=1-5, and R^(A) and R^(B) are each hydrogenor a hydrocarbyl group. Preferably, n=1-3, and more preferably n=1.Preferably, the conjugated diene comprises at least one conjugated dienehaving at least four carbon atoms and a formula corresponding to theconjugated dienes of formulae (1) or (3) described above. Followingpolymerization, the original unsaturation in the polymerized conjugateddiene has a formula corresponding to formulae (2) or (4) as describedabove.

Following polymerization the substituted styrene-diene copolymer ispreferably functionalized by a method which includes selectivelyhydrogenating the copolymer to provide a selectively hydrogenatedcopolymer, followed by functionalizing the selectively hydrogenatedcopolymer to provide a functionalized copolymer having at least onepolar functional group.

The polymers of this embodiment include a ring-substituted styrene in anamount of from about 0.5% wt. to about 25% wt., and a conjugated dienein an amount of from about 75% wt. to about 99.5% wt. Preferably, aring-substituted styrene is included in an amount of from about 1% wt.to about 20% wt., and a conjugated diene in an amount of from about 80%to about 99% wt. More preferably, a ring-substituted styrene is includedin an amount of from about 5% wt. to about 15% wt., and a conjugateddiene is included in an amount of from about 85% to about 95% wt.

In the dispersant substances of this embodiment, a ring-substitutedstyrene and a conjugated diene are preferably polymerized as a blockcopolymer comprising at least two alternating blocks:

    (P).sub.x -(B).sub.y or (B).sub.y -(P).sub.x,

wherein the block (P) includes at least one polymerized ring-substitutedstyrene of formula (5), and the block (B) includes at least onepolymerized conjugated diene of formulae (1) or (3). In addition, x isthe number of polymerized monomer units in block (P) and is at least 1,and y is the number of polymerized monomer units in block (B) and is atleast 25. Preferably, in the block copolymers of this embodiment, x isfrom about 1 to about 600, and y is from about 30 to about 4,000, morepreferably x is from about 1 to about 350, and y is from about 30 toabout 2,800.

Alternatively, a ring-substituted styrene and a conjugated diene arepolymerized as a random copolymer. In addition, a ring-substitutedstyrene and a conjugated diene may be polymerized as a branched orstar-branched random or block copolymer.

The copolymers useful according to this embodiment typically have amolecular weight of at least about 2,000. Preferably, the molecularweight of these polymers is from about 2,000 to about 1,000,000, morepreferably from about 5,000 to about 500,000. The molecular weightdistribution of these polymers is preferably about 1.01 to about 1.20.

The dispersant substances of this embodiment include a copolymer whichcan be selectively hydrogenated to retain as much of the originalaromatic unsaturation a possible, while removing as much of the originalunsaturation of formulae (2) or (4) as possible. Preferably, followinghydrogenation, the residual unsaturation of formulae (2) or (4) is fromabout 0% to about 1% of the Iodine Number prior to the hydrogenationreaction. More preferably, after the hydrogenation reaction, the IodineNumber for the residual unsaturation of formulae (2) or (4) is fromabout 0% to about 0.5% of the Iodine Number prior to the hydrogenationreaction. Most preferably, after the hydrogenation reaction, the IodineNumber for the residual unsaturation of formulae (2) or (4) is about 0%of the Iodine Number prior to the hydrogenation reaction.

Preferably, following the selective hydrogenation, the aromaticunsaturation of the substituted styrene monomer is at least about 50%retained, more preferably at least about 90% retained, and mostpreferably about 100% retained.

In the dispersant substances of this embodiment, the ring-substitutedstyrene component of the polymer preferably includes an alkylstyrene,such as vinyl toluene, vinyl xylene, methylstyrene, ethylstyrene,propylstyrene, isopropylstyrene, sec-butylstyrene, or benzylstyrene, ormixtures thereof. More preferably, the ring-substituted styrene includesp-methylstyrene.

In the dispersant substances of this embodiment, the conjugated dienemay include one or more conjugated dienes of formulae (1) or (3) asdescribed elsewhere herein. Preferably, the conjugated diene includes aconjugated diene of formula (1) such as isoprene,2,3-dimethyl-butadiene, 2-methyl-1,3-pentadiene, myrcene,3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene,2-phenyl-1,3-butadiene, 2-phenyl-1,3-pentadiene, 3-phenyl-1,3pentadiene, 2,3-dimethyl-1,3-pentadiene, 2-hexyl-1,3-butadiene,3-methyl-1,3-hexadiene, 2-benzyl-1,3-butadiene, 2-p-tolyl-1,3-butadiene,or mixtures thereof, and/or a conjugated diene of formula (3) such as1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, 1,3-hexadiene,1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene, 2,4-octadiene,3,5-octadiene, 1,3-nonadiene, 2,4-nonadiene, 3,5-nonadiene,1,3-decadiene, 2,4-decadiene, 3,5-decadiene, or mixtures thereof.

More preferably, the conjugated diene of formula (1) includes isoprene,myrcene, 2,3-dimethyl-butadiene, or 2-methyl-1,3-pentadiene. Mostpreferably, the conjugated diene of formula (1) includes isoprene. Morepreferably, the conjugated diene of formula (3) includes 1,3-butadiene,1,3-pentadiene, or 1,3-hexadiene. Most preferably, the conjugated dieneof formula (3) includes 1,3-butadiene.

In the copolymers of this embodiment, when the conjugated diene includes1,3-butadiene, the polymerized butadiene include a mixture of 1,4- and1,2-units. Preferably, the conjugated dienes include at least about 25%,more preferably from about 30% to about 90%, and most preferably fromabout 45% to about 65%, of the 1,2-units.

Also in this embodiment, the selectively hydrogenated polymer is morepreferably chemically modified to provide a polymer with at least onehalogen functional group. Preferably, the halogen functional groupincludes bromine. To impart dispersant properties, it is more preferredto further modify the polymer, e.g., by reacting the halogen group withan amine, a polyamine, or a combination thereof.

In still another embodiment, the invention is directed to homopolymersof a conjugated diene, selected from among any of the dienes of formulae(1) and (3) described above. Preferred conjugated dienes of formula (1)include isoprene, myrcene, 2,3-dimethyl-butadiene, or2-methyl-1,3-pentadiene. Preferred conjugated dienes of formula (3)include 1,3-butadiene or 1,3-pentadiene. The polymerized diene may beprepared in linear, branched, or star-branched form. The homopolymer maybe subjected to selective hydrogenation to provide a partiallyhydrogenated polymer, retaining a sufficient amount of the originalunsaturation to functionalize the polymer.

Any of the dispersant substances of the invention may include afunctionalized polymer of the invention distributed in a carrier fluidsuch as a synthetic or mineral oil, to provide a dispersant concentrate.The dispersant concentrates generally include the polymer in an amountof from about 5% wt. to about 90% wt., more preferably from about 10%wt. to about 70% wt., of the dispersant substance, depending upon themolecular weight of the polymer.

The dispersant substances may further include at least one additiveselected from the group consisting of antioxidants, pour pointdepressants, detergents, dispersants, friction modifiers, anti-wearagents, anti-foam agents, corrosion and rust inhibitors, Viscosity indeximprovers, and the like.

The invention further provides a method of modifying the dispersancy orviscometric properties of a fluid such as a lubricant. The methodincludes admixing with a fluid an amount of a dispersant substance ofthe invention which is sufficient provide a dispersant-modified fluidhaving dispersancy or viscometric properties which are altered from theoriginal fluid. Preferably, the method involves admixing the dispersantsubstance in an amount of from about 0.001% wt. to about 20% wt., morepreferably from about 0.1% wt. to about 10% wt., and most preferablyfrom about 0.5% wt. to about 7% wt., of the dispersant-modified fluid.Typically, the method of the invention is employed to modify lubricatingoils and normally liquid fuels; such as motor oils, transmission fluids,hydraulic fluids, gear oils, aviation oils, and the like. In addition,the method may further include admixing with the fluid at least oneadditive such as antioxidants, pour point depressants, detergents,dispersants, friction modifiers, anti-wear agents, anti-foam agents,corrosion and rust inhibitors, viscosity index improvers, and the like.

The invention also provides a dispersant-modified fluid, such as ahydrocarbon fluid, having modified dispersancy or viscometricproperties. In this embodiment, the dispersant-modified fluid typicallyincludes a mineral or synthetic oil and a dispersant substance of theinvention. Preferably, the dispersant-modified fluid of the inventionincludes a dispersant substance in an amount of from about 0.001% wt. toabout 20% wt., more preferably from about 0.1% wt. to about 10% wt., andmost preferably from about 0.5% wt. to about 7% wt., of the modifiedlubricating fluid. The dispersant-modified fluid preferably includes amineral or synthetic lubricating oil or a normally liquid fuel; such asmotor oils, transmission fluids, hydraulic fluids, gear oils, aviationoils, and the like. These dispersant-modified fluids may further includeat least one additive such as antioxidants, pour point depressants,detergents, dispersants, friction modifiers, anti-wear agents, anti-foamagents, corrosion and rust inhibitors, viscosity index improvers, andthe like.

The copolymers of all embodiments are prepared under anionicpolymerization conditions. Following polymerization, the polymers of theinvention are selectively hydrogenated to provide a controlled amountand extent of residual unsaturation. After the selective hydrogenationreaction, the hydrogenation catalyst is removed from the polymer and thepolymer is chemically modified of functionalized to impart desirablecharacteristics for the dispersant substances of the invention.

Accordingly, as a result of the invention, there are now provideddispersants, dispersants with VI-improving properties, and dispersant VIimprovers prepared by polymerization of conjugated dienes, followed byselective hydrogenation and functionalization. These dispersantsubstances of the invention possess numerous advantages, includingcontrolled molecular weight, controlled molecular weight distribution,controlled polymer structure, variable and controlled amounts anddistribution of functionality, superior thermal stability, potentiallypermitting reduced treat levels and yielding benefits such as improvedviscometric properties.

These and other advantages of the present invention will be appreciatedfrom the detailed description and examples which are set forth herein.The detailed description and examples enhance the understanding of theinvention, but are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention have been chosen for purposes ofillustration and description, but are not intended in any way torestrict the scope of the present invention. The preferred embodimentsof certain aspects of the invention are shown in the accompanyingdrawings, wherein:

FIG. 1 shows the relationship of viscosity as a function of molecularweight for the unhydrogenated isoprene-butadiene-isoprene triblockpolymer of this invention.

FIG. 2 shows the relationship of viscosity as a function of molecularweight for the hydrogenated isoprene-butadiene-isoprene triblock polymerof this invention.

FIG. 3 shows the dispersancy characteristics of two commercialdispersants as compared to dispersants of the invention.

FIG. 4 shows the dispersancy characteristics of two commercialdispersants as compared to dispersants of the invention.

FIG. 5 shows the dispersancy characteristics of two commercialdispersants as compared to a dispersant of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The polymeric dispersants of the invention, typically having lowermolecular weights, can be employed in any lubricant or fuel compositionthat requires a dispersant to control the deposition of sludge particleson, for example, engine parts. Other polymeric substances of theinvention, typically those having higher molecular weights, may beemployed for their VI-improving properties in any lubricant fluid whichmay benefit from a modification of its viscometric properties. Thesecompounds may also find a variety of uses in addition to lubricantadditives, such as adhesives, sealants, impact modifiers, and the like.

As noted above, traditional dispersants have been polybutenesfunctionalized via an ene reaction with maleic anhydride followed byimidization with a polyamine. The polybutenes are typically 500-2,000 inmolecular weight. With one olefin per polybutene molecule, the number ofpotential functional groups per chain is limited to one. Consequently,the molecular weight of polybutene may not exceed 2,000 if the desiredfunctionality/hydrocarbon ratio is to be maintained.

By contrast, with this invention, the amount of residual unsaturationcan be controllably varied. As a result, the amount of functionality onewishes to incorporate is quite flexible. In addition, the molecularweight of the polymer backbone is not limited to 2,000. Higher molecularweight polymers can be prepared and functionalized such that the samefunctionality/hydrocarbon ratio that is found in the traditionaldispersant is maintained if so desired. Moreover, with this invention,the position of the functionality is not limited to the end of thepolymer chain as it is with polybutenes. Instead, a variety of optionsis now available, including, for example, randomly along the backbone,at one end, at both ends, or in the center, of the polymer chain.

If a polymer according to the invention is of sufficiently highmolecular weight (e.g., 20,000-50,000), it will exhibit increasedthickening power and viscosity index-improving (VI-improving)properties, as well as sludge dispersing ability. Hence, the use ofthese materials may permit reduction in use of both traditionaldispersants and VI. If materials are prepared with backbones that are≧50,000 in molecular weight, the functionalized versions can beclassified as dispersant VI improvers or VI improvers with dispersantproperties. Their dispersant capabilities are outstanding for dispersantVI improvers.

In one embodiment, the present invention provides polymers including atleast two different conjugated dienes, wherein one of the dienes is moresubstituted in the 2, 3, and 4 carbon positions than the other diene.The more substituted diene produces vinylidene, tri-, ortetra-substituted double bonds after polymerization. Hydrogenation ofthe material is done selectively so as to saturate the lessersubstituted olefins, which primarily arise from the lesser substituteddiene, while leaving a portion of the more substituted conjugatedolefins behind for functionalizing.

In this embodiment, the more substituted conjugated diene will have atleast five (5) carbon atoms and the following formula: ##STR6## whereinR¹ -R⁶ are each hydrogen (H) or a hydrocarbyl group, provided that atleast one of R¹ -R⁶ is a hydrocarbyl group. After polymerization, theunsaturation in the polymerized conjugated diene of formula (1) has thefollowing formula: ##STR7## wherein R^(I), R^(II), R^(III) and R^(IV)are each hydrogen or a hydrocarbyl group, provided that either bothR^(I) and R^(II) are hydrocarbyl groups or both R^(III) and R^(IV) arehydrocarbyl groups. Examples of conjugated dienes of formula 1 includeisoprene, 2,3-dimethylbutadiene, 2-methyl-1,3-pentadiene, myrcene, andthe like. Isoprene is highly preferred.

The lesser substituted conjugated diene in this embodiment differs fromthe other diene in that it has at least four (4) carbon atoms and thefollowing formula: ##STR8## wherein R⁷ -R¹² are each hydrogen or ahydrocarbyl group. After polymerization, the unsaturation in thepolymerized conjugated diene of formula (3) has the following formula:##STR9## wherein R^(V), R^(VI), R^(VII) and R^(VIII) are each hydrogen(H) or a hydrocarbyl group, provided that one of R^(V) or R^(VI) ishydrogen, one of R^(VII) or R^(VIII) is hydrogen, and at least one ofR^(V), R^(VI), R^(VII) and R^(VIII) is a hydrocarbyl group. Examples ofthe conjugated diene of formula (3) include 1,3-butadiene,1,3-pentadiene, 2,4-hexadiene, and the like. A highly preferredconjugated diene of formula 3 is 1,3-butadiene.

An exception to this scheme would be when a tetra-substituted diene,e.g., 2,3-dimethylbutadiene, is used for the more substituted component(1), When this occurs, a tri-substituted olefin, e.g., isoprene, may beused for the lesser substituted component (3), such that one or both ofR^(V) and R^(VI) are hydrogen and both R^(VII) and R^(VIII) arehydrocarbyl.

It will be apparent to those skilled in the art that in the originalunsaturation of formula (2), R^(I), R^(II), R^(III) and R^(IV) may allbe hydrocarbyl groups, whereas in the original unsaturation of formula(4) at least one of R^(V), R^(VI), R^(VII) and R^(VIII) must be ahydrogen.

The hydrocarbyl group or groups in the formulae (1) to (4) are the sameor different and they are substituted or unsubstituted alkyl, alkenyl,cycloalkyl, cycloalkenyl, aryl, alkaryl, or aralkyl groups, or anyisomers thereof.

The copolymers of this embodiment are prepared by anionicallypolymerizing a diene of formula (1) at a level of from about 0.5% wt. toabout 25% wt., and a diene of formula (3) at a level of from about 75%wt. to about 99.5% wt., in a hydrocarbon solvent using an alkyllithiumcatalyst. The two monomers can be polymerized in block, tapered block,or random fashion. Since the polymerization is anionic, the molecularweight distribution of these copolymers is typically very narrow,generally ranging from about 1.01 to about 1.20, and is determined bythe ratio of monomer to initiator and/or by the presence of couplingagents.

The monomers (1) and (3) may be polymerized either simultaneously or instepwise fashion depending on the desired position of the remainingunsaturation after hydrogenation. If random positioning of theunsaturation is desired, both monomers are reacted together to give arandom copolymer. If it is desirable to have the functionality on onlyone end, then the monomers are reacted in stepwise fashion, the orderbeing determined as desired, to provide a diblock copolymer. Iffunctionality is needed on both ends, then a conjugated diene of formula(1) is polymerized first, followed by a diene of formula (3). To theliving anion, a coupling agent, e.g., phenyl benzoate or methylbenzoate, is then added to yield a desired triblock copolymer.Alternatively, a diene of formula (1) may be added to the living diblockto give the triblock. A fourth approach would allow the functionality tobe positioned in the center of the polymer chain. In this case, a dieneof formula (3) is polymerized first, followed by a diene of formula (1),and then a third block of diene of formula (3) is added by couplingagent or through the living anion of the diblock. In addition,combinations of the above approaches may be employed.

The present invention also includes copolymers that are prepared from aring-substituted styrene and a conjugated diene, preferablyp-methylstyrene and 1,3-butadiene. More specifically, the materials aregenerated by anionically polymerizing a ring-substituted styrene (about0.5 wt. % to about 25 wt. %) and a diene (about 99.5 wt. % to about 75wt. %). The monomers can be polymerized either in block, tapered block,or random fashion. For a random distribution of the ring-substitutedstyrene, it is necessary to polymerize the two monomers in the presenceof a substantial quantity of a polar modifier or to slowly add the dieneto polymerizing ring-substituted styrene.

The scope of this embodiment includes ring-substituted styrenes thathave at least one benzylic hydrogen and possess the formula: ##STR10##wherein n=1-5, and R^(A) and R^(B) are independently hydrogen or analkyl group. More preferably, n=1-3, and most preferably n=1. Theconjugated diene in this embodiment may be selected from among thedienes having formula (1) or (3) as described elsewhere herein.

This embodiment includes functionalized versions of the ring-substitutedstyrene-conjugated diene copolymers described above.Functionality-introducing reactions such as halogenation are carried outon the copolymers in a separate post-hydrogenation step. The halogenatedcopolymers are then further modified, typically by a reaction involvinga monoamine or a polyamine.

The invention is further directed to homopolymers of a conjugated diene.The conjugated diene may selected from any of the dienes described inrelation to formulae (1) and (3) described elsewhere herein. Thesepolymers have preferably been partially hydrogenated such that theypossess an Iodine Number of 1-150, preferably 2-100. The unsaturationremaining after hydrogenation is used to incorporate polar functionalityalong the backbone of the polymer. These functionalized materials may beused as lubricant additives. Functionalization may be accomplished byreacting with an unsaturated carboxylic acid derivative via the enereaction or via a radical addition. Preferably, the acylated polymer isthen further modified by reacting with a monamine or a polyamine. Othermodification methods such as halogenation, epoxidation, hydroxylation,and the like, may be used.

The invention can include polymers of differing microstructures. Thepresence of polar modifier increases the activity of the catalyst and,therefore, increase the level of 1,2-microstructure over1,4-microstructure in polybutadiene, for example. The percentage ofvinyl obtained is directly proportional to the concentration of themodifier employed. Since the reaction temperature also plays a role indetermining the microstructure of polybutadiene, the level of modifiermust be chosen taking into account the combined effects. Antkowiak etal. have presented a way for quickly determining the proper conditionsfor preparation of any 1,2-microstructure content within a range of fromabout 10% to about 80%. Use of this method or any others to achieve thedesired microstructure will be known to anyone who is skilled in theart.

The dispersants and dispersant VI improvers of the invention can includedifferent polymer macrostructures. Polymers may be prepared and utilizedhaving linear and/or nonlinear, e.g., star-branched, macrostructures.The star-branched polymers can be prepared by addition of divinylbenzeneor the like to the living polymer anion. Lower levels of branching canbe obtained through the use of tri-functional or tetra-functionalcoupling agents, such as tetrachlorosilane.

The invention also includes dispersant polymers wherein the polymersinclude an additional aryl-substituted olefin such as styrene,p-methylstyrene, vinyl naphthalene, etc. The aryl substituted olefin maybe incorporated randomly throughout the polymer, randomly in one or twoof the blocks with another monomer, or in a tapered block or pure blockat any position along the polymer. Thus, any of the (I) and (B) blocksmay include an aryl-substituted olefin in an amount of up to about 30%wt. The random copolymers and homopolymers of the invention can alsoinclude an aryl-substituted olefin in an amount of up to about 30% wt.

If an aryl-substituted olefin is incorporated into a higher molecularweight polymer of the invention in a pure block or tapered blockfashion, the resulting material will have reduced cold flow. A lack ofcold flow is a trait which is desirable for higher molecular weight VIimprovers since the bulk polymer resists flowing at temperatures atwhich it would normally be stored prior to use in a lube oil (e.g., upto about 140° F.). It is generally preferred that the VI improver have acrumb or particulate form which retains its shape during storage. Also,the retention of the shape of the crumbs enhances the ease ofsolubilization of the polymers because their relatively large surfacearea is preserved.

In all embodiments of this invention, whenever a reference is made tothe "original double bond" or the "original unsaturation" of the blockor random polymer (or copolymer), it is understood to mean the doublebond(s) in the polymer prior to the hydrogenation reaction. By contrast,the terms "residual double bond(s)" and "residual unsaturation", as usedherein, refer to the unsaturated group(s), typically excluding aromaticunsaturation, present in the copolymer after the selective hydrogenationreaction.

The molecular structure of the original or residual double bonds can bedetermined in any conventional manner, as is known to those skilled inthe art, e.g., by infrared (IR) or nuclear magnetic resonance (NMR)analysis. In addition, the total original or residual unsaturation ofthe polymer can be quantified in any conventional manner, e.g., byreference to the Iodine Number of the polymer.

In any polymers of any of the embodiments of this invention, themicrostructure of the polymerized conjugated diene of formula (3) mustbe such that the polymer is not excessively crystalline after theselective hydrogenation reaction. That is, after the selectivehydrogenation reaction the polymer must retain its elastomericproperties, e.g., the polymer should contain not more than about 10% ofpolyethylene crystallinity. Generally, problems of crystallinity occuronly when the polymer includes polymerized 1,3-butadiene. Limitingpolymeric crystallinity may be accomplished in various ways. Forexample, this is accomplished by introducing side branches into thepolymerized conjugated dienes of formulae (1) and/or (3), e.g., bycontrolling the microstructure of 1,3-butadiene if it is the predominantmonomer in the diene of formula (3); by using a mixture of dienes offormula (3) containing less than predominant amounts of 1,3-butadiene;or by using a single diene of formula (3), other than 1,3-butadiene.More particularly, if the conjugated diene(s) of formula (3) ispredominantly (at least 50% by mole) 1,3-butadiene, the side branchesare introduced into the polymer by insuring that the polymerized dieneof formula (3) contains a sufficient amount of the 1,2-units to preventthe selectively hydrogenated polymer from being excessively crystalline.Thus, if the conjugated diene of formula (3) is predominantly (at least50% by mole, e.g., 100% by mole) 1,3-butadiene, the polymerized diene offormula (3), prior to the selective hydrogenation reaction, must containnot more than about 75% wt., preferably from about 10% wt. to about 70%wt., and most preferably from about 35% wt. to about 55% wt. of the1,4-units, and at least about 25% wt., preferably from about 30% wt. toabout 90% wt., and most preferably from about 45% wt. to about 65% wt.of the 1,2-units. If the polymerized diene(s) of formula (3) containsless than 50% by mole of 1,3-butadiene, e.g., 1,3-pentadiene is used asthe only diene of formula (3), the microstructure of the polymerizeddiene of formula (3) prior to the selective hydrogenation reaction isnot critical since, after hydrogenation, the resulting polymer willcontain substantially no crystallinity.

In all embodiments of the invention, mixtures of dienes of formulae (1)or (3) may be used to prepare block copolymers (I)_(x) -(B)_(y) or anyof the random copolymers or star-branched block and random polymers ofthe invention. Similarly, mixtures of aryl-substituted olefins may alsobe used to prepare block, random, or star-branched copolymers of thisinvention. Accordingly, whenever a reference is made herein to a dieneof formulae (1) or (3), or to an aryl-substituted olefin, it mayencompass more than one diene of formulae (1) or (3), respectively, andmore than one aryl-substituted olefin.

The block copolymers of this invention comprise two or more alternatingblocks, identified above. Linear block copolymers having two blocks andblock copolymers having three or more blocks are contemplated herein.However, star-branched block polymers containing any combination andnumber of blocks (I) and (B), or (P) and (B), are also contemplatedherein.

The block polymers useful according to the invention typically includeat least one block which is substantially completely saturated, whilealso including at least one block containing controlled levels ofunsaturation providing a hydrocarbon elastomer with selectivelypositioned unsaturation for subsequent functionalization. For thecopolymers prepared from two different conjugated dienes, it has beenfound the that two dienes in the copolymers hydrogenate at differentrates, permitting selective control of the placement of residualunsaturation. For copolymers prepared from a ring-substituted styreneand a conjugated diene, it has been found that aromatic unsaturation andthe olefinic unsaturation hydrogenate at different rates, againpermitting control and placement of the residual unsaturation.

Many variations in composition, molecular weight, molecular weightdistribution, relative block lengths, microstructure, branching, andT_(g) (glass transition temperature) attainable with the use of anionictechniques employed in the preparation of our polymers will be obviousto those skilled in the art.

While not wishing to limit the molecular weight range of liquidelastomers prepared according to our invention, the minimum molecularweight for these liquid polymers is at least about 2,000, preferablyabout 2,000 to about 1,000,000, and most preferably about 5,000 to about500,000. The star-branched block and random copolymers and homopolymersof this invention may have substantially higher molecular weights andstill retain liquid properties. The block copolymers of this inventionare functionalizable. Without wishing to be bound by any theory ofoperability, it is believed that they can be functionalized in acontrolled manner through the unsaturated groups on the terminal blocksto provide dispersants and dispersant VI improvers having almost uniformdistribution of molecular weights. The star-branched and linear versionsof the random copolymers and homopolymers of this invention are alsofunctionalizable.

All numerical values of molecular weight given in this specification andthe drawings are of number average molecular weight (M_(n)).

The invention will be described hereinafter in terms of the embodimentsthereof summarized above. However, it will be apparent to those skilledin the art, that the invention is not limited to these particularembodiments, but, rather, it covers all the embodiments encompassed bythe broadest scope of the description of the invention.

Copolymers From at Least Two Dissimilar Conjugated Dienes

In this embodiment of the invention, there are provided copolymers oftwo dissimilar conjugated dienes, preferably isoprene and 1,3-butadiene.The two monomers can be polymerized by anionic polymerization process ineither a block, tapered block, or random fashion.

Th copolymers of this embodiment include a first conjugated diene havingat least five (5) carbon atoms and the following formula: ##STR11##wherein R¹ -R⁶ are each hydrogen or a hydrocarbyl group, provided thatat least one of R¹ -R⁶ is a hydrocarbyl group, and further providedthat, when polymerized, the structure of the double bond in thepolymerized conjugated diene of formula (1) has the following formula:##STR12## wherein R^(I), R^(II), R^(III) and R^(IV) are each hydrogen ora hydrocarbyl group, provided that either both R^(I) and R^(II) arehydrocarbyl groups or both R^(III) and R^(IV) are hydrocarbyl groups. Inthe double bond of the polymerized conjugated diene of formula (2),R^(I), R^(II), R^(III) and R^(IV) may all be hydrocarbyl groups.

The polymers of this embodiment also include a second conjugated diene,different from the first conjugated diene, having at least four (4)carbon atoms and the following formula: ##STR13## wherein R⁷ -R¹² areeach hydrogen or a hydrocarbyl group, provided that the structure of thedouble bond in the polymerized conjugated diene of formula (3) has thefollowing formula: ##STR14## wherein R^(V), R^(VI), R^(VII) and R^(VIII)are each hydrogen (H) or a hydrocarbyl group, provided that one of R^(V)or R^(VI) is hydrogen, one of R^(VII) or R^(VIII) is hydrogen, and atleast one of R^(V), R^(VI), R^(VII) and R^(VIII) is a hydrocarbyl group.

Following polymerization the diene copolymer of this embodiment ispreferably functionalized by a method which includes selectivelyhydrogenating the copolymer to provide a selectively hydrogenatedcopolymer, followed by functionalizing the selectively hydrogenatedcopolymer to provide a functionalized copolymer having at least onepolar functional group.

The polymers of this embodiment include a first conjugated diene offormula (1) in an amount of from about 0.5% wt. to about 25% wt., and asecond conjugated diene in an amount of from about 75% wt. to about99.5% wt. Preferably, a first conjugated diene is included in an amountof from about 1% wt. to about 20% wt., and a second conjugated diene inan amount of from about 80% to about 99% wt. More preferably, a firstconjugated diene is included in an amount of from about 5% wt. to about15% wt., and a second conjugated diene is included in an amount of fromabout 85% to about 95% wt.

The polymers of this embodiment include block copolymers having at leasttwo alternating blocks:

    (I).sub.x -(B).sub.y or (B).sub.y -(I).sub.x.

In this case, the polymer includes at least one block (I). The block (I)is a block of at least one polymerized conjugated diene of formula (1)as described above. These block copolymers also include at least onepolymerized block (B). The block (B) is a block of at least onepolymerized conjugated diene of formula (3) described above.

In the block copolymers of this embodiment, x is at least 1, preferablyfrom about 1 to about 600, and most preferably from about 1 to about350. The above definition of x means that each of the (I) blocks ispolymerized from at least 1, preferably about 1-600, and more preferablyabout 1-350, monomer units.

In the block copolymers of this embodiment, y is at least 25, preferablyfrom about 30 to about 4,000, more preferably from about 30 to about2,800. The above definition of y means that each of the (B) blocks ispolymerized from at least 25, preferably about 30-4,000, and morepreferably about 30-2,800, monomer units.

The block copolymer comprises about 0.5 to about 25%, preferably about 1to about 5% by wt. of the (I) blocks, and about 75 to about 99.5%,preferably about 95 to about 99% by wt. of the (B) blocks.

In any of the copolymers of this embodiment, the structures of thedouble bonds defined by formulae (2) and (4) are necessary to producecopolymers which can be selectively hydrogenated in the manner describedherein, to produce the selectively hydrogenated block and randomcopolymers of this invention.

The hydrocarbyl group or groups in the formulae (1) and (2) are the sameor different and they are substituted or unsubstituted alkyl, alkenyl,cycloalkyl, cycloalkenyl, aryl, alkaryl, or aralkyl groups, or anyisomers thereof. Suitable hydrocarbyl groups are alkyls of 1-20 carbonatoms, alkenyls of 1-20 carbon atoms, cycloalkyls of 5-20 carbon atoms,aryls of 6-12 carbon atoms, alkaryls of 7-20 carbon atoms or aralkyls of7-20 carbon atoms. Examples of suitable alkyl groups are methyl, ethyl,propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, methyl-decyl ordimethyl-decyl. Examples of suitable alkenyl groups are ethenyl,propenyl, butenyl, pentenyl or hexenyl. Examples of suitable cycloalkylgroups are cyclohexyl or methylcyclohexyl. Examples of suitablecycloalkenyl groups are 1-, 2-, or 3-cyclohexenyl or4-methyl-2-cyclohexenyl. Examples of suitable aryl groups are phenyl ordiphenyl. Examples of suitable alkaryl groups are 4-methyl-phenyl(p-tolyl) or p-ethyl-phenyl. Examples of suitable aralkyl groups arebenzyl or phenethyl. Suitable conjugated dienes of formula (1) used topolymerize the (I) block are isoprene, 2,3-dimethyl-butadiene,2-methyl-1,3-pentadiene, myrcene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, 2-phenyl-1,3-butadiene,2-phenyl-1,3-pentadiene, 3-phenyl-1,3 pentadiene,2,3-dimethyl-1,3-pentadiene, 2-hexyl-1,3-butadiene,3-methyl-1,3-hexadiene, 2-benzyl-1,3-butadiene, 2-p-tolyl-1,3-butadiene,or mixtures thereof, preferably isoprene, myrcene,2,3-dimethyl-butadiene, or 2-methyl-1,3-pentadiene, and most preferablyisoprene.

The hydrocarbyl group or groups in the formula (3) may or may not be thesame as those in formula (4). These hydrocarbyl groups are the same asthose described above in conjunction with the discussion of thehydrocarbyl groups of formulae (1) and (2). Suitable monomers for the(B) block are 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene,1,3-hexadiene, 1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene,2,4-octadiene, 3,5-octadiene, 1,3-nonadiene, 2,4-nonadiene,3,5-nonadiene, 1,3-decadiene, 2,4-decadiene, 3,5-decadiene, or mixturesthereof, preferably 1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, or1,3-hexadiene, and most preferably it is 1,3-butadiene. It is generallypreferred that each of the (B) blocks is polymerized from a singlemonomer.

The scope of this embodiment, and of any other embodiments of theinvention wherein the block (B) is used, also encompasses polymerswherein the block (B) may comprise copolymers of one or more conjugateddiene of formula (3) and controlled amounts (about 0.3 to about 30 mole%) of an aryl-substituted olefin, e.g., styrene or other suitablemonomers (such as alkylated styrene, vinyl naphthalene, or alkylatedvinyl naphthalene) incorporated for control of glass transitiontemperature (T_(g)), density, solubility parameters and refractiveindex. Suitable aryl-substituted olefins are those described below inconjunction with another of the embodiments of the invention. Similarly,the scope of this embodiment also encompasses polymers wherein the block(B) may be comprised of copolymers of one or more conjugated diene offormula (3) and any other anionically polymerizable monomer capable ofpolymerizing with the conjugated diene of formula (3). Similarconsiderations also apply in the case of the (I) block(s), which caninclude similar styrene/diene copolymers.

The copolymer is polymerized by any conventional copolymerizationprocess, preferably anionic polymerization, discussed in detail below.As will be apparent to those skilled in the art, the block copolymer ofthis embodiment contains at least two alternating blocks, (I)-(B) or(B)-(I), referred to herein as diblocks. The block copolymer of thisembodiment may contain three alternating blocks, e.g., (I)-(B)-(I),referred to, herein as triblocks or triblock units, but it may containan unlimited number of blocks. The functionalization of any of thesecopolymers is conducted in a conventional manner and is described below.

After the (I)-(B) copolymer is polymerized, it is subjected to aselective hydrogenation reaction during which the polymerized conjugateddienes of formula (3) of the copolymer are selectively hydrogenated tosuch an extent that they contain substantially none of the originalunsaturation, while the polymerized conjugated dienes of formula (1) ofthe copolymer retain a sufficient amount of their original unsaturationto permit functionalization.

Generally, for a copolymer wherein the conjugated dienes of formulae (1)and (3) are polymerized to provide unsaturation of formulae (2) and (4),respectively, as discussed above, the Iodine Number for the unsaturationof formula (2) after the selective hydrogenation reaction is from about20% to about 100%, preferably from about 50% to about 100%, and mostpreferably about 100%, of the Iodine Number prior to the selectivehydrogenation reaction; and for the unsaturation of formula (4) it isfrom about 0% to about 10%, preferably from about 0% to about 0.5%, andmost preferably from about 0% to about 0.2%, of the Iodine Number priorto the selective hydrogenation reaction. The Iodine Number, as is knownto those skilled in the art, is defined as the theoretical number ofgrams of iodine which will add to the unsaturation in 100 grams ofolefin and is a quantitative measure of unsaturation.

In this embodiment of the invention, although the microstructure of the(I) blocks is not critical and may consist of 1,2-, 3,4- and/or1,4-units, schematically represented below for the polyisoprene blocks,when a polar compound is used during the polymerization of the (I)block, the (I) blocks comprise primarily (at least about 50% wt.)3,4-units, the rest being primarily (less than about 50% wt.) 1,4-units;when the polar compound is not used during the polymerization of the (I)block, the (I) blocks comprise primarily (about 80% wt.) 1,4-units, therest being primarily 1,2- and 3,4-units. ##STR15##

The microstructure of the (B) blocks, when the predominant monomer usedto polymerize the (B) blocks is 1,3-butadiene, should be a mixture of1,4- and 1,2- units schematically shown below for the polybutadieneblocks: ##STR16## since the hydrogenation of the predominantly1,4-microstructure produces a crystalline polyethylene segment. Themicrostructure of the (I) and (B) blocks (as well as of the polymerizedconjugated dienes of formulae (1) or (3) in any polymers of thisinvention) is controlled in a conventional manner, e.g., by controllingthe amount and nature of the polar compounds used during thepolymerization reaction, and the reaction temperature. In oneparticularly preferred embodiment, the (B) block contains about 50% ofthe 1,2- and about 50% of the 1,4-microstructure. If the (B) block ispoly-1,3-butadiene, the hydrogenation of the (B) segment containing fromabout 50% to about 60% of the 1,2-microstructure content produces anelastomeric center block which is substantially an ethylene-butene-1copolymer having substantially no crystallinity. If the (B) block ispolymerized from 1,3-pentadiene, it is preferred that it havepredominantly (at least 50%) of 1,4-microstructure which, afterhydrogenation, produces a substantially non-crystalline elastomericblock.

The terms "1,2-", "1,4-", and "3,4-microstructure" or "units" as used inthis application refer to the products of polymerization obtained by the1,2-, 1,4- and 3,4-, respectively, mode of addition of monomer units.

We surprisingly discovered that the polymerized conjugated dienes offormula (3), e.g., the dienes employed in (B) blocks, of the polymers ofthis invention are selectively hydrogenated in our hydrogenation processmuch faster than the polymerized conjugated dienes of formula (1), e.g.,the dienes used in the (I) blocks. This is not evident from theteachings of Falk, discussed above, because Falk teaches that doublebonds of the di-substituted 1,4-polybutadiene units are hydrogenatedselectively in the presence of double bonds of the tri-substituted1,4-polyisoprene units (which hydrogenate very slowly). We surprisinglydiscovered that the di-substituted double bonds of the 1,4-polybutadieneunits are hydrogenated along with the monosubstituted double bonds ofthe 1,2-polybutadiene units, while the di-substituted double bonds ofthe 3,4-polyisoprene units are hydrogenated at a much slower rate thanthe aforementioned polybutadienes. Thus, in view of Falk's disclosure itis surprising that the di-substituted double bonds of the1,4-polybutadiene units are hydrogenated selectively in the presence ofthe di-substituted double bonds of the 3,4-polyisoprene units. This isalso surprising in view of the teachings of Hoxmeier, Published EuropeanPatent Application, Publication No. 0 315 280, who discloses that thedi-substituted double bonds of the 1,4-polybutadiene units,monosubstituted double bonds of the 1,2-polybutadiene units anddi-substituted double bonds of the 3,4-polyisoprene units arehydrogenated simultaneously at substantially the same rates. Forexample, for the block copolymers of this invention, wherein the (I)block is polyisoprene and the (B) block is polybutadiene, FourierTransform Infrared (FTIR) analysis of selectively hydrogenated blockcopolymers of the invention, such as I-B-I triblock polymers, indicatesthat the hydrogenation of the double bonds of the 1,2-polybutadieneunits proceeds most rapidly, followed by the hydrogenation of the doublebonds of the 1,4-polybutadiene units. Infrared absorptions caused bythese groups disappear prior to appreciable hydrogenation of thepolyisoprene units.

Accordingly, by controlling the amount and placement of 1,2-versus1,4-microstructure, as well as the amount and placement of polyisopreneunits, it is now possible to control the amount and placement ofunsaturation remaining in the polymers after hydrogenation. It followsthat the amount and placement of functionalization of the polymericdispersants of the invention is also controllable to an extent notpossible previously.

After the block copolymer is prepared, it is subject to a selectivehydrogenation reaction to hydrogenate primarily the (B) block(s). Theselective hydrogenation reaction and the catalyst are described indetail below. After the hydrogenation reaction is completed, theselective hydrogenation catalyst is removed from the block copolymer,and the polymer is isolated by conventional procedures, e.g., alcoholflocculation, steam stripping of solvent, or non-aqueous solventevaporation. An antioxidant, e.g., Irganox 1076 (from Ciba-Geigy), isnormally added to the polymer solution prior to polymer isolation.

Copolymers of a Ring-Substituted Styrene and a Conjugated Diene

The present invention also includes copolymers that are prepared from atleast one ring-substituted styrene and at least one conjugated diene,preferably p-methylstyrene and 1,3-butadiene. More specifically, thematerials are generated by anionically polymerizing a ring-substitutedstyrene and a conjugated diene. The monomers can be polymerized eitherin block, tapered block, or random fashion. For a random distribution ofthe ring-substituted styrene, it is necessary to polymerize the twomonomers in the presence of a substantial quantity of a polar modifieror to slowly add the diene to polymerizing ring-substituted styrene.

The scope of this embodiment includes polymers which include aring-substituted styrene having at least one benzylic hydrogen andpossessing the formula: ##STR17## wherein n=1-5, and R^(A) and R^(B) areindependently hydrogen or an alkyl group. Preferably, n=1-3, morepreferably n=1. The ring-substituted styrene is preferably selected fromp-alkylstyrenes, such as vinyl toluenes, vinyl xylenes, methylstyrenes,ethylstyrenes, propylstyrenes, isopropylstyrenes, or sec-butylstyrenes,or benzyl styrenes; or a mixture thereof. Most preferably thering-substituted styrene includes p-methylstyrene.

The conjugated diene in this embodiment may be selected from among thedienes having formula (1) or (3) as described elsewhere herein. Mostpreferably, the conjugated diene includes 1,3-butadiene.

Following polymerization the diene copolymer is preferablyfunctionalized by a method which includes selectively hydrogenating thecopolymer to provide a selectively hydrogenated copolymer, followed byfunctionalizing the selectively hydrogenated copolymer to provide afunctionalized copolymer having at least one polar functional group.

The polymers of this embodiment preferably include a ring-substitutedstyrene in an amount of from about 0.5% wt. to about 25% wt., and aconjugated diene in an amount of from about 75% wt. to about 99.5% wt.More preferably, a ring-substituted styrene is included in an amount offrom about 5% wt. to about 15% wt., and a conjugated diene in an amountof from about 85% to about 95% wt.

This embodiment includes block copolymers of a ring-substituted styreneand a conjugated diene, wherein the block copolymer includes at leasttwo alternating blocks:

    (P).sub.x -(B).sub.y

wherein the block (P) includes at least one polymerized ring-substitutedstyrene of formula (5) defined above, and the block (B) includes atleast one polymerized conjugated diene of formula (1) or (3).

Preferably, in the block copolymers of this embodiment, x is from about1 to about 600, and y is from about 30 to about 4,000, more preferably xis from about 1 to about 350, and y is from about 30 to about 2,800.

These copolymers, whether random, block or tapered block, linear,branched or star-branched, are preferably selectively hydrogenatedaccording to the methods described elsewhere herein. The selectivehydrogenation process operates to hydrogenate the original olefinicunsaturation in a controllable fashion, leaving the polymer with aselected amount of residual aromatic unsaturation. The selection of theconjugated diene in the polymer serves as a basis for controlling therate and extent of hydrogenation of the polymer. Followinghydrogenation, the Iodine Number of these polymers is from about 0% toabout 1%, preferably from about 0% to about 0.4%, and more preferablyfrom about 0% to about 0.1%, and most preferably about 0%, of the IodineNumber prior to the hydrogenation procedure.

The aromatic unsaturation, by contrast is preferably substantiallyretained following the selective hydrogenation. Preferably, followingselective hydrogenation the polymer retains at least about 50% of itsoriginal aromatic unsaturation. More preferably, following selectivehydrogenation the copolymer retains at least about 90% of its originalaromatic unsaturation.

This embodiment also includes functionalized versions of thering-substituted styrene-conjugated diene copolymers described above.Functionality-introducing reactions, preferably halogenation, followedby reaction with an amine or a polyamine, are carried out on thecopolymers in a separate post-hydrogenation step.

Random Copolymers

Random copolymers of this invention have controlled amounts ofunsaturation incorporated randomly in an otherwise saturated backbone.In contrast to EPDM, the level of unsaturation can be inexpensively andeasily controlled, e.g., to produce polymers having Iodine Number offrom about 5 to about 100, to provide a wide variation in the degree offunctionalization.

In one embodiment, the random copolymers are polymerized from the samemonomers used to polymerize the block copolymers (I)_(x) -(B)_(y),described elsewhere herein. In particular, the random copolymers may bemade by polymerizing at least one conjugated diene of formula (1) withat least one conjugated diene of formula (3), both defined above,provided that the diene of formula (1) is different from the diene offormula (3). This random copolymer contains from about 1.0% to about40%, preferably from about 1.0% to about 20%, by mole of the polymerizedconjugated diene of formula (1) and from about 60% to about 99%,preferably from about 80% to about 99% by mole of the polymerizedconjugated diene of formula (3). Suitable conjugated dienes of formula(1) are exemplified above. The most preferred conjugated diene offormula (1) for the copolymerization of these random copolymers isisoprene. Suitable conjugated dienes of formula (3) are also exemplifiedabove. 1,3-butadiene is the most preferred conjugated diene of formula(3) for the polymerization of the random copolymer of this embodiment.Thus, most preferably, in this embodiment, the random copolymer ispolymerized from isoprene and 1,3-butadiene, and it contains from about1% wt. to about 20% wt. of the isoprene units and from about 80% wt. toabout 99% wt. of the butadiene units. The isoprene units have primarily(i.e., from about 50% wt. to about 90% wt.) the 3,4-microstructure.

In another embodiment, the random copolymers are polymerized from thesame monomers used to polymerize the block copolymers (P)_(x) -(B)_(y),described elsewhere herein. In this case, the random copolymers are madeby polymerizing at least one ring-substituted styrene and at least oneconjugated diene of formulae (1) or (3). The polymers of this embodimentpreferably include a ring-substituted styrene in an amount of from about0.5% wt. to about 25% wt., and a conjugated diene in an amount of fromabout 75% wt. to about 99.5% wt. More preferably, a ring-substitutedstyrene is included in an amount of from about 5% wt. to about 15% wt.,and a conjugated diene in an amount of from about 85% to about 95% wt.

The random copolymers are subjected to the selective hydrogenationreaction discussed above for the block copolymers, during whichpolymerized conjugated diene units of formulae (1) or (3) aresubstantially completely hydrogenated, while the aromatic unsaturationis hydrogenated to a substantially lesser extent, i.e., to such anextent that they retain a sufficient amount of their originalunsaturation to functionalize the copolymer, thereby producingdispersants and dispersant VI improvers having random unsaturationproportional to the unsaturation in the polymerized dienes of formula(1). For example, for random copolymer polymerized from a diene offormula (1) and a different diene of formula (3), the Iodine Numberbefore selective hydrogenation for the polymer is about 450. Afterselective hydrogenation, the Iodine Number for the polymer is from about10 to about 50, with most of the unsaturation being contributed by thediene of formula (1).

The hydrogenated polymers may be functionalized. The degree offunctionalization of the polymers can be easily and inexpensivelyincreased by increasing the content of the diene of formula (1), i.e.,isoprene in the most preferred embodiment, in either embodiment of therandom copolymers to from about 5% to about 20% by mole.

Star-Branched Polymers

The invention is also directed to star-branched block and randompolymers. The star-branched block polymers are made from any combinationof blocks (I) and (B) and (P), all defined above.

The star-branched (I)-(B) block polymers comprise from about 0.5% wt. toabout 25% wt., preferably from about 1% wt. to about 5% wt., of the (I)blocks, and from about 75% wt. to about 99.5% wt., preferably from about95% wt. to about 99% wt., of the (B) blocks.

The star-branched (P)-(B) block polymers comprise from about 0.5% wt. toabout 25% wt., preferably from about 1% wt. to about 5% wt., of the (P)blocks, and from about 75% wt. to about 99.5% wt., preferably from about95% wt. to about 99% wt., of the (B) blocks.

The star-branched block polymers are selectively hydrogenated in theselective hydrogenation process of this invention to such an extent thatblocks (B) contain substantially none of the original unsaturation,while each of the blocks (I) respectively, retains a sufficient amountof the original unsaturation of the conjugated dienes present in theseblocks to functionalize the star-branched block polymers. Thus, for theI-(B) star-branched block polymer, after the selective hydrogenationreaction, the Iodine Number for the (I) blocks is from about 10% toabout 100%, preferably from about 25% to about 100%, more preferablyfrom about 50% to about 100%, and most preferably about 100%, of theIodine Number prior to the selective hydrogenation reaction; and for the(B) blocks it is from about 0% to about 10%, preferably from about 0% toabout 0.5%, of the Iodine Number prior to the selective hydrogenationreaction.

Similarly, for the (P)-(B) star-branched block polymer, after theselective hydrogenation reaction, the Iodine Number for the (B) blocksis from about 0% to about 1%, preferably from about 0% to about 0.5%,and most preferably 0%, of the Iodine Number prior to the selectivehydrogenation reaction. The (P) blocks preferably retain as mucharomatic unsaturation as possible following hydrogenation. Preferably,the (P) block retain at least about 50%, more preferably at least about90%, and most preferably about 100%, or their original aromaticunsaturation.

The star-branched random polymers are made from any combination of atleast one diene of formula (1) and at least one diene of formula (3),different from the diene of formula (1), or from any combination of atleast one ring-substituted styrene and at least one diene of formulae(1) or (3), all of which are the same as those discussed above. Thestar-branched random polymers of the dienes of formulae (1) and (3),which must be different from each other, comprise from about 1% wt. toabout 25% wt., preferably from about 1% wt. to about 10% wt., of thediene of formula (1), and from about 75% wt. to about 99% wt.,preferably from about 90% wt. to about 99% wt., of the diene of formula(3). The star-branched random polymers of the ring-substituted styreneand the diene of formulae (1) or (3) comprise from about 1% wt. to about25% wt., preferably from about 1% wt. to about 10% wt., of thering-substituted styrene, and from about 75% wt. to about 99% wt.,preferably from about 90% wt. to about 99% wt., of the diene of formulae(1) or (3).

The star-branched random diene polymers are also selectivelyhydrogenated in the selective hydrogenation process of this invention tosuch an extent that the polymerized dienes of formula (3) containsubstantially none of the original unsaturation, while the polymerizeddienes of formula (1) retain a sufficient amount of the originalunsaturation to functionalize the star-branched random polymers. Thus,for the star-branched random polymer of the conjugated diene of formula(1) and a different diene of formula (3), both identified above, theIodine Number for the polymerized diene of formula (1), after theselective hydrogenation reaction, is from about 10% to about 100%,preferably from about 25% to about 100%, more preferably from about 50%to about 100%, and most preferably about 100%, of the Iodine Numberprior to the selective hydrogenation reaction; and for the polymerizeddiene of formula (3) it is from about 0% to about 10%, preferably fromabout 0% to about 0.5%, of the Iodine Number prior to the selectivehydrogenation reaction.

Homopolymers of a Conjugated Diene

The invention is further directed to diene homopolymers which have beenpartially hydrogenated such that they possess an iodine number of 1-150,preferably 2-100. The residual unsaturation is used to incorporate polarfunctionality along the backbone of the polymer. These functionalizedmaterials may be used as lubricant additives. Functionalization may beaccomplished as described herein, preferably by reacting with anunsaturated carboxylic acid derivative via the ene reaction or via aradical addition. The acylated polymer is preferably then furthermodifed by being reacted with a monamine or a polyamine. Othermodification methods such as halogenation, epoxidation, hydroxylation,and the like, may be used.

The homopolymers and random copolymers of the invention are polymerizedand/or coupled in a similar fashion, but all monomers, e.g., isopreneand butadiene, are mixed in a proper ratio prior to the reaction withthe polar compound-modified alkyl-lithium. In homopolymer and randompolymer preparation, of course, only one stage is necessary.

Polymerization Reaction

The polymers of this invention are polymerized by any knownpolymerization processes, preferably by an anionic polymerizationprocess. Anionic polymerization is well known in the art and it isutilized in the production of a variety of commercial polymers. Anexcellent comprehensive review of the anionic polymerization processesappears in the text Advances in Polymer Science 56, "AnionicPolymerization", pp. 1-90, Springer-Verlag, Berlin, Heidelberg, NewYork, Tokyo 1984 in a monograph entitled Anionic Polymerization ofNon-polar Monomers Involving Lithium, by R. N. Young, R. P. Quirk and L.J. Fetters, incorporated herein by reference. The anionic polymerizationprocess is conducted in the presence of a suitable anionic catalyst(also known as an initiator), such as n-butyl-lithium,sec-butyl-lithium, t-butyl-lithium, sodium naphthalide or, cumylpotassium. The amount of the catalyst and the amount of the monomer inthe polymerization reaction dictate the molecular weight of the polymer.The polymerization reaction is conducted in solution using an inertsolvent as the polymerization medium, e.g., aliphatic hydrocarbons, suchas hexane, cyclohexane, or heptane, or aromatic solvents, such asbenzene or toluene. In certain instances, inert polar solvents, such astetrahydrofuran, can be used alone as a solvent, or in a mixture with ahydrocarbon solvent.

The polymerization process will be exemplified below for thepolymerization of one of the embodiments of the invention, andspecifically for the preferred embodiment thereof, i.e., a triblock ofpolyisoprene-polybutadiene-polyisoprene. However, it will be apparent tothose skilled in the art that the same process principles can be usedfor the polymerization of all polymers of the invention.

The process, when using a lithium-based catalyst, comprises forming asolution of the isoprene monomer in an inert hydrocarbon solvent, suchas cyclohexane, modified by the presence therein of one or more polarcompounds selected from the group consisting of ethers, thioethers, andtertiary amines, e.g., tetrahydrofuran. The polar compounds arenecessary to control the microstructure of the butadiene center block,i.e., the content of the 1,2-structure thereof. The higher the contentof the polar compounds, the higher will be the content of the1,2-structure in these blocks. Since the presence of the polar compoundis not essential in the formation of the first polymer block with manyinitiators unless a high 3,4-structure content of the first block isdesired, it is not necessary to introduce the polar compound at thisstage, since it may be introduced just prior to or together with theaddition of the butadiene in the second polymerization stage. Examplesof polar compounds which may be used are dimethyl ether, diethyl ether,ethyl methyl ether, ethyl propyl ether, dioxane, diphenyl ether,dipropyl ether, tripropyl amine, tributyl amine, trimethyl amine,triethyl amine, and N-N-N'-N'-tetramethyl ethylene diamine. Mixtures ofthe polar compounds may also be used. The amount of the polar compounddepends on the type of the polar compound and the polymerizationconditions as will be apparent to those skilled in the art. The effectof polar compounds on the polybutadiene microstructure is detailed inAntkowiak et al., "Temperature and Concentration Effects onPolar-modified Alkyl Lithium Polymerizations and Copolymerizations,"Journal of Polymer Science: Part A-1, 10: 1319-34 (1972), incorporatedherein by reference. The polar compounds also accelerate the rate ofpolymerization. If monomers other than 1,3-butadiene, e.g., pentadiene,are used to polymerize the central blocks (B), polar compounds are notnecessary to control the microstructure because such monomers willinherently produce polymers which do not possess crystallinity afterhydrogenation.

When the alkyl lithium-based initiator, a polar compound and an isoprenemonomer are combined in an inert solvent, polymerization of the isopreneproceeds to produce the first terminal block whose molecular weight isdetermined by the ratio of the isoprene to the initiator. The "living"polyisoprenyl anion formed in this first step is utilized as thecatalyst for further polymerization. At this time, butadiene monomer isintroduced into the system and block polymerization of the second blockproceeds, the presence of the polar compound now influencing the desireddegree of branching (1,2-structure) in the polybutadiene block. Theresulting product is a living diblock polymer having a terminal anionand a lithium counterion. The living diblock polymer serves as acatalyst for the growth of the final isoprene block, formed whenisoprene monomer is again added to the reaction vessel to produce thefinal polymer block, resulting in the formation of the I-B-I triblock.Upon completion of polymerization, the living anion, now present at theterminus of the triblock, is destroyed by the addition of a protondonor, such as methyl alcohol or acetic acid. The polymerizationreaction is usually conducted at a temperature of between about 0° C.and about 100° C., although higher temperatures can be used. Control ofa chosen reaction temperature is desirable since it can influence theeffectiveness of the polar compound additive in controlling the polymermicrostructure. The reaction temperature can be, for example, from about50° C. to about 80° C. The reaction pressure is not critical and variesfrom about atmospheric to about 100 psig.

If the polar compounds are utilized prior to the polymerization of thefirst (I) segment, (I) blocks with high 3,4-unit content are formed. Ifpolar compounds (some of which can be Lewis bases) are added after theinitial (I) segment is prepared, the first (I) segment will possess ahigh percentage of 1,4-microstructure (which is tri-substituted), andthe second segment will have a high percentage of 3,4-microstructure.

The production of triblock polymers having a high 1,4-unit content onboth of the terminal (I) blocks is also possible by the use of couplingtechniques illustrated below for apolyisoprene-polybutadiene-polyisoprene block copolymer: ##STR18##

The substitution of myrcene for the isoprene during the polymerizationof the (I) blocks insures the incorporation of a high proportion oftri-substituted double bonds, even in the presence of polar compoundssince myrcene contains a pendant tri-substituted double bond which isnot involved in the polymerization process. In a coupling process,similar to that described above, block polymers containing polyisopreneend blocks (or any other polymerized monomer suitable for use in the (I)block) having a high 3,4-microstructure content can be obtained byadding the polar compound prior to the isoprene (or another monomer)polymerization.

The use of the coupling technique for the production of triblockpolymers reduces the reaction time necessary for the completion ofpolymerization, as compared to sequential addition of isoprene, followedby butadiene, followed by isoprene. Such coupling techniques are wellknown and utilize coupling agents, such as esters, CO₂, iodine,dihaloalkanes, silicon tetrachloride, divinyl benzene, alkyltrichlorosilanes and dialkyl dichlorosilanes. The use of tri- ortetra-functional coupling agents, such as alkyl trichlorosilanes orsilicon tetrachloride, permits the formation of macromolecules having 1-or 2-main chain branches, respectively. The addition of divinyl benzeneas a coupling agent has been documented to produce molecules having upto 20 or more separately joined segments.

The use of some of the coupling agents provides a convenient means ofproducing star-branched block and random polymers. The star-branchedblock polymers are made from any combination of blocks (I) and (B), or(P) and (B), defined above. The star-branched random polymers are madefrom any combination of at least one diene of formula (1) and at leastone diene of formula (3), different from the diene of formula (1), orfrom at least one aryl-substituted olefin, at least one diene of formula(1) and at least one diene of formula (3), different from the diene offormula (1). The molecular weight of the star-branched block and randomcopolymers will depend on the number of branches in each such copolymer,as will be apparent to those skilled in the art. Suitable couplingagents and reactions are disclosed in the following references which areincorporated herein by reference: U.S. Pat. Nos. 3,949,020; 3,594,452;3,598,887; 3,465,065; 3,078,254; 3,766,301; 3,632,682; 3,668,279; andGreat Britain patents 1,014,999; 1,074,276; 1,121,978.

Selective Hydrogenation

Following polymerization, selective hydrogenation of the polymer may beaccomplished using techniques similar to those known in the art. Apreferred method and catalyst are described in U.S. Pat. No. 5,187,236,the disclosure of which is incorporated herein by reference. Theprocedure and catalyst are described in greater detail below. Ingeneral, however, the previously described polymers can be contactedwith hydrogen and a hydrogenation catalyst synthesized from a transitionmetal compound, typically nickel or cobalt, and a organometallicreducing agent, e.g., triethylaluminum. The hydrogenation proceeds attemperatures typically not in excess of about 40° C. and at pressures offrom about 30 psi to about 200 psi. Generally, the polymers arehydrogenated such that substantially all of the unsaturation in formula(2) is removed, while much of that from formula (4) is retained.Alternatively, if it is desirable to functionalize one of the copolymersin a combined VI improver so as to provide the polymer with a secondarytrait, e.g., antioxidancy or dispersancy, a selective hydrogenation maybe performed leaving residual vinylidene or tri-substituted olefins fromthe isoprene which can later be modified. Any other known selectivehydrogenation methods may be used, as will be apparent to those skilledin the art, but the method described above is one which is preferred.

The selective hydrogenation reaction will also be described below usinga triblock of polyisoprene-polybutadiene-polyisoprene as an example.However, it will be apparent to those skilled in the art that anypolymers of this invention can be selectively hydrogenated in the samemanner.

The block copolymer is selectively hydrogenated to saturate the middle(polybutadiene) block of each of the triblocks. The method ofselectively hydrogenating the polybutadiene block is similar to that ofFalk, "Coordination Catalysts for the Selective Hydrogenation ofPolymeric Unsaturation", Journal of Polymer Science: Part A-1, 9:2617-23 (1971), but it is conducted with a novel hydrogenation catalystand process used herein. Any other known selective hydrogenation methodsmay also be used, as will be apparent to those skilled in the art, butit is preferred to use the method described herein. In summary, theselective hydrogenation method preferably used herein comprisescontacting the previously-prepared block copolymer with hydrogen in thepresence of the novel catalyst composition.

The novel hydrogenation catalyst composition and hydrogenation processare described in detail in previously cited application Ser. No.07/466,136. The hydrogenation catalyst composition is synthesized fromat least one transition metal compound and an organometallic reducingagent. Suitable transition metal compounds are compounds of metals ofGroup IVb, Vb, VIb or VIII, preferably IVb or VIII of the Periodic Tableof the Elements, published in Lange's Handbook of Chemistry, 13th Ed.,McGraw-Hill Book Company, New York (1985) (John A. Dean, ed.).Non-limiting examples of such compounds are metal halides, e.g.,titanium tetrachloride, vanadium tetrachloride; vanadium oxytrichloride,titanium and vanadium alkoxides, wherein the alkoxide moiety has abranched or unbranched alkyl radical of 1 to about 20 carbon atoms,preferably 1 to about 6 carbon atoms. Preferred transition metalcompounds are metal carboxylates or alkoxides of Group IVb or VIII ofthe Periodic Table of the Elements, such as nickel (II)2-ethylhexanoate, titanium isopropoxide, cobalt (II) octoate, nickel(II) phenoxide and ferric acetylacetonate.

The organometallic reducing agent is any one or a combination of any ofthe materials commonly employed to activate Ziegler-Natta olefinpolymerization catalyst components containing at least one compound ofthe elements of Groups Ia, IIa, IIb, IIIa, or IVa of the Periodic Tableof the Elements. Examples of such reducing agents are metal alkyls,metal hydrides, alkyl metal hydrides, alkyl metal halides, and alkylmetal alkoxides, such as alkyllithium compounds, dialkylzinc compounds,trialkylboron compounds, trialkylaliminum compounds, alkylaluminumhalides and hydrides, and tetraalkylgermanium compounds. Mixtures of thereducing agents may also be employed. Specific examples of usefulreducing agents include n-butyllithium, diethylzinc, di-n-propylzinc,triethylboron, diethylaluminumethoxide, triethylaluminum,trimethylaluminum, triisobutylaluminum, tri-n-hexylaluminum,ethylaluminum dichloride, dibromide, and dihydride, isobutyl aluminumdichloride, dibromide, and dihydride, diethylaluminum chloride, bromide,and hydride, di-n-propylaluminum chloride, bromide, and hydride,diisobutylaluminum chloride, bromide and hydride, tetramethylgermanium,and tetraethylgermanium. Organometallic reducing agents which arepreferred are Group IIIa metal alkyls and dialkyl metal halides having 1to about 20 carbon atoms per alkyl radical. More preferably, thereducing agent is a trialkylaluminum compound having 1 to about 6 carbonatoms per alkyl radical. Other reducing agents which can be used hereinare disclosed in Stevens et al., U.S. Pat. No. 3,787,384, column 4, line45 to column 5, line 12 and in Strobel et al., U.S. Pat. No. 4,148,754,column 4, line 56 to column 5, line 59, the entire contents of both ofwhich are incorporated herein by reference. Particularly preferredreducing agents are metal alkyl or hydride derivatives of a metalselected from Groups Ia, IIa and IIIa of the Periodic Table of theElements, such as n-butyl lithium, sec-butyl lithium, n-hexyl lithium,phenyl-lithium, triethylaluminum, tri-isobutylaluminum,trimethylaluminum, diethylaluminum hydride and dibutylmagnesium.

The molar ratio of the metal derived from the reducing agent to themetal derived from the transition metal compound will vary for theselected combinations of the reducing agent and the transition metalcompound, but in general it is about 1:1 to about 12:1, preferably about1.5:1 to about 8:1, more preferably about 2:1 to about 7:1, and mostpreferably about 2.5:1 to about 6:1. It will be apparent to thoseskilled in the art that the optimal ratios will vary depending upon thetransition metal and the organometallic agent used, e.g., for thetrialkylaluminum/nickel(II) systems, the preferred aluminum:nickel molarratio is about 2.5:1 to about 4:1, for the trialkylaluminum/cobalt(II)systems, the preferred aluminum:cobalt molar ratio is about 3:1 to about4:1, and for the trialkylaluminum/titanium(IV) alkoxides systems, thepreferred aluminum:titanium molar ratio is about 3:1 to about 6:1.

The mode of addition and the ratio of the reducing agent to thetransition metal compound are important in the production of the novelhydrogenation catalyst having superior selectivity, efficiency andstability, as compared to prior art catalytic systems. During thesynthesis of the catalysts it is preferred to maintain the molar ratioof the reactants used to synthesize the catalyst substantially constant.This can be done either by the addition of the reducing agent, asrapidly as possible, to a solution of the transition metal compound, orby a substantially simultaneous addition of the separate streams of thereducing agent and the transition metal compound to a catalyst synthesisvessel in such a manner that the selected molar ratios of the metal ofthe reducing agent to the metal of the transition metal compound aremaintained substantially constant throughout substantially the entiretime of addition of the two compounds. The time required for theaddition must be such that excessive pressure and heat build-up areavoided, i.e., the temperature should not exceed about 80° C. and thepressure should not exceed the safe pressure limit of the catalystsynthesis vessel.

In a preferred embodiment, the reducing agent and the transition metalcompound are added substantially simultaneously to the catalystsynthesis vessel in such a manner that the selected molar ratio of thereducing agent to the transition metal compound is maintainedsubstantially constant during substantially the entire time of theaddition of the two compounds. This preferred embodiment permits thecontrol of the exothermic reaction so that the heat build-up is notexcessive, and the rate of gas production during the catalyst synthesisis also non excessive--accordingly, the gas build-up is relatively slow.In this embodiment, carried out with or without a solvent diluent, therate of addition of the catalyst components is adjusted to maintain thesynthesis reaction temperature at or below about 80° C., which promotesthe formation of the selective hydrogenation catalyst. Furthermore, theselected molar ratios of the metal of the reducing agent to the metal ofthe transition metal compound are maintained substantially constantthroughout the entire duration of the catalyst preparation when thesimultaneous mixing technique of this embodiment is employed.

In another embodiment, the catalyst is formed by the addition of thereducing agent to the transition metal compound. In this embodiment, thetiming and the order of addition of the two reactants is important toobtain the hydrogenation catalyst having superior selectivity,efficiency and stability. Thus, in this embodiment, it is important toadd the reducing agent to the transition metal compound in that order inas short a time period as practically possible. In this embodiment, thetime allotted for the addition of the reducing agent to the transitionmetal compound is critical for the production of the novel catalyst. Theterm "as short a time period as practically possible" means that thetime of addition is as rapid as possible, such that the reactiontemperature is not higher than about 80° C. and the reaction pressuredoes not exceed the safe pressure limit of the catalyst synthesisvessel. As will be apparent to those skilled in the art, that time willvary for each synthesis and will depend on such factors as the types ofthe reducing agents, the transition metal compounds and the solventsused in the synthesis, as well as the relative amounts thereof, and thetype of the catalyst synthesis vessel used. For purposes ofillustration, a solution of about 15 mL of triethylaluminum in hexaneshould be added to a solution of nickel(II) octoate in mineral spiritsin about 10-30 seconds. Generally, the addition of the reducing agent tothe transition metal compound should be carried out in about 5 seconds(sec) to about 5 minutes (min), depending on the quantities of thereagents used. If the time period during which the reducing agent isadded to the transition metal compound is prolonged, e.g., more than 15minutes, the synthesized catalyst is less selective, less stable, andmay be heterogeneous.

In the embodiment wherein the reducing agent is added as rapidly aspossible to the transition metal compound, it is also important to addthe reducing agent to the transition metal compound in theaforementioned sequence to obtain the novel catalyst. The reversal ofthe addition sequence, i.e., the addition of the transition metalcompound to the reducing agent, or the respective solutions thereof, isdetrimental to the stability, selectivity, activity, and homogeneity ofthe catalyst and is, therefore, undesirable.

In all embodiments of the hydrogenation catalyst synthesis, it ispreferred to use solutions of the reducing agent and the transitionmetal compound in suitable solvents, such as hydrocarbon solvents, e.g.,cyclohexane, hexane, pentane, heptane, benzene, toluene, or mineraloils. The solvents used to prepare the solutions of the reducing agentand of the transition metal compound may be the same or different, butif they are different, they must be compatible with each other so thatthe solutions of the reducing agent and the transition metal compoundare fully soluble in each other.

The hydrogenation process comprises contacting the unsaturated polymerto be hydrogenated with an amount of the catalyst solution containingabout 0.1 to about 0.5, preferably about 0.2 to about 0.3 mole percentof the transition metal based on moles of the polymer unsaturation. Thehydrogen partial pressure is generally from about 5 psi to about severalhundred psi, but preferably it is from about 10 psi to about 100 psi.The temperature of the hydrogenation reaction mixture is generally fromabout 0° C. to about 150° C., preferably from about 25° C. to about 80°C., more preferably from about 30° C. to about 60° C., since highertemperatures may lead to catalyst deactivation. The length of thehydrogenation reaction may be as short as 30 minutes and, as will beapparent to those skilled in the art, depends to a great extent on theactual reaction conditions employed. The hydrogenation process may bemonitored by any conventional means, e.g., infra-red spectroscopy,hydrogen flow rate, total hydrogen consumption, or any combinationthereof.

Upon completion of the hydrogenation process, unreacted hydrogen iseither vented or consumed by the introduction of the appropriate amountof an unsaturated material, such as 1-hexene, which is converted to aninert hydrocarbon, e.g., hexane. Subsequently, the catalyst is removedfrom the resulting polymer solution by any suitable means, selecteddepending on the particular process and polymer. For a low molecularweight material, for example, catalyst residue removal may consist of atreatment of the solution with an oxidant, such as air, and subsequenttreatment with ammonia and optionally methanol in amounts equal to themolar amount of the metals (i.e., the sum of the transition metal andthe metal of the reducing agent) present in the hydrogenation catalystto yield the catalyst residues as a filterable precipitate, which isfiltered off. The solvent may then be removed by any conventionalmethods, such as vacuum stripping, to yield the product polymer as aclear, colorless fluid.

Alternatively, and in a preferred embodiment, upon completion of thehydrogenation reaction, the mixture is treated with ammonia in the molaramount about equal to that of the metals (i.e., the sum of thetransition metal and the metal of the reducing agent) and aqueoushydrogen peroxide, in the molar amount equal to about one half to aboutone, preferably one half, of the amount of the metals. Other levels ofthe ammonia and peroxide are also operative, but those specified aboveare particularly preferred. In this method, a precipitate forms, whichmay be filtered off as described above.

In yet another alternative method, the catalyst may be removed byextraction with an aqueous mineral acid, such as sulfuric, phosphoric,or hydrochloric acid, followed by washing with distilled water. A smallamount of a material commonly used as an aid in removing transitionmetal-based catalysts, such as a commercially available high molecularweight diamine, e.g., Jeffamine D-2000 from Texaco, may be added to aidin phase separation and catalyst removal during the extractions. Theresultant polymer solution is then dried over a drying agent, such asmagnesium sulfate, separated from the drying agent and the solvent isthen separated by any conventional methods, such as vacuum stripping, toyield a polymer as a clear fluid. Other methods of polymer isolation,such as steam or alcohol flocculation, may be employed depending uponthe hydrogenated polymer properties.

After hydrogenation and purification is complete, the polymer can befunctionalized and used in the lubricant compositions of the invention:the liquids will serve as dispersants and the solids as dispersant VIimprovers.

Functionalization of the Polymers

The unsaturated terminal blocks of the block polymers of this inventioncan be chemically modified to provide benefits which enhance thedispersancy and viscosity improving qualities of the materials of theinvention. Such benefits may be obtained through methods similar tothose employed for the modification of existing commercial materials,such as butyl rubber or EPDM.

Following the selective hydrogenation step, the remaining sites ofunsaturation are chemically modified. Such methods include reacting theunsaturated groups in the polymer with any of various reagents toproduce functional groups, such as hydroxyl, epoxy, sulfonic acid,mercapto, acrylate or carboxyl groups. Functionalization methods arewell known in the art.

A preferred chemical modification method involves reaction of thepolymer with an unsaturated carboxylic acid derivative, such as acrylicacid, maleic acid, fumaric acid, maleic anhydride, methacrylate, and thelike. Most preferably, maleic anhydride is used for modification ofunsaturation. Numerous methods are known for the modification ofpolybutene and EPDM via the ene reaction. Methods are also known for thereaction of maleic anhydride with EPM via a radical reaction in thepresence of a radical initiator. Either method can be adapted toincorporate the unsaturated carboxylic acid derivatives into thepolymeric dispersants of the invention.

In a preferred functionalization of diene copolymers, the selectivelyhydrogenated copolymer is functionalized with a functional groupsselected from among halogens, epoxies, sulfonic acids, and carboxylicacid derivatives, and subsequently modified further by reacting with amonoamine, a polyamine, or a combination thereof.

The ene reaction of maleic anhydride with materials of the invention canbe performed on solutions of the polymers in light mineral oil orpolyalphaolefin at temperatures of from about 150° C. to about 250° C.,typically under an inert atmosphere. Such modification of the polymersof any embodiments of our invention occurs readily, since the residualisoprene unsaturation, primarily of the 3,4-type, illustrated above, isknown to be more reactive with maleic anhydride than are the internalbonds found in EPDM.

Other functionality-introducing reactions such as halogenation may becarried out post-hydrogenation. Halogenation, preferably bromination, ismade to occur by a radical reaction, wherein, heat, light, or a radicalinitiator, may be used. Halogenation processes are described, forexample, in European Patent Application No. EP 0 344 021.

Subsequent to the acylation reaction (or other suitable modification asoutlined above), the modified polymers are reacted with a monoamine, apolyamine, or a combination thereof. The amines which are useful forthis modification reaction are characterized by the presence of at leastone primary (i.e., H₂ N--) or secondary (i.e., HN═) amino group. Theamines can be aliphatic amines, cycloaliphatic amines, heterocyclicamines, aromatic amines, polyamines, or hydroxyamines. Preferably, thepolyamines contain only one primary or secondary amine, with theremaining amines being tertiary (i.e., --N═) or aromatic amines. theamination can be accomplished by heating the maleic anhydride-modifieddiene polymer to about 150° C. in the presence of the amine, followed bystripping off the water.

With respect to polymers of the invention which include ring-substitutedstyrene units, in order to obtain exclusive substitution at the benzylicposition, the polymers should not contain any in-chain (backbone)olefinic unsaturation. Halogenation may be accomplished by methods knownin the art, such as the method described in European Patent ApplicationNo. EP 0 344 021. Amination can then be accomplished by heating thehalogenated ring-substituted styrene-diene copolymer in the presence ofthe amine.

The above description illustrates only some of the potentially valuablechemical modification of the polymers of this invention. The polymers ofthis invention provide a means for a wide variety of chemicalmodifications at selected sites in the polymer, e.g., only at the endsof a triblock polymer molecule (i.e., at the (I) blocks only), therebypresenting the opportunity to prepare materials previously impossiblebecause of the lack of availability of such polymers. Some examples ofwell known chemical reactions which can be performed on polymers of thisinvention are found in E. M. Fettes, "Chemical Reactions of Polymers",High Polymers, Vol. 19, John Wiley, New York, (1964), incorporatedherein by reference.

Dispersant and VI-Improving Applications

The polymers of the invention, whether block copolymers, tapered blockcopolymers, branched and star branched polymers, random copolymers, orhomopolymers, have been unexpectedly found to have the capacity tomodify the dispersancy and/or viscometric properties of fluids, such asmineral and synthetic oil lubricants and normally liquid fuels.Accordingly, it is within the scope of the invention that the dispersantpolymers of the invention be employed in dispersant substances which canbe added to fluids to modify the dispersancy and/or viscometricproperties of the fluids. The invention, thus, also includes a method ofmodifying or improving the dispersancy and/or viscometric properties ofa fluid by admixing with the fluid a sufficient amount of a dispersantsubstance of the invention so as to obtain or provide a modified orimproved fluid having modified or improved dispersancy and/orviscometric properties. Moreover, the invention also includesdispersant-modified or dispersant-improved fluids to which have beenadded a dispersant substance of the invention so as to modify thedispersancy and/or viscometric properties of the fluid.

The improvement of viscometric properties includes any one or more ofthe properties of fluids which are related to viscosity. The dispersantVI improvers of the invention specifically improve the viscosity indexof such fluids. Viscosity index is a property characterizing therelationship between the viscosity of a fluid and temperature.Improvement in viscosity index is characterized by a decrease in therate of change of viscosity per unit of temperature change. Typicalproperties which are modified or improved by the dispersant VI improversof the invention include relative thickening power (RTP), borderlinepumpability, permanent shear stability (DIN), temporary shear stabilityat low temperatures (CCS), and temporary shear stability at hightemperatures (HTHS). Each of these properties can be determined orcharacterized by conventional methods.

The polymers of the invention may be employed as dispersants and/ordispersant VI improvers in a variety of lubricant fluids, Typically,such fluid is a mineral oil such as a mineral oil lubricant system,e.g., motor oils, automatic transmission fluids, tractor hydraulicfluids, gear oils, aviation oils, and the like. Other suitableapplications include normally liquid fuels. The lubricant or fuel may benaturally occurring or synthetic, or a combination thereof. Natural oilsinclude mineral oils obtained from petroleum, including distillate andresidual lubricating oils, and the like. Synthetic oils can includeliquid esters, fluorocarbons, polyethers, polysilicones, and the like.The dispersants can be added to a lubricant or fuel formulation in anysuitable and effective amount to modify the dispersancy and/orviscometric properties of the formulation. An exemplary broad range isfrom about 0.001% wt. to about 20% wt., preferably from about 0.1% wt.to about 10% wt., more preferably from about 0.5% wt. to about 7% wt.,of the formulation.

The polymers of the invention can be supplied neat or as an oilconcentrate. Some of the polymers of the invention have cold flowproperties, thereby making it difficult to transport such polymersexcept as a concentrate. However, for ease of handling, the polymers canbe prepared as a liquid concentrate. Typically, such dispersantconcentrates include a polymer of the invention in an amount of fromabout 5% wt. to about 90% wt., preferably from about 10% wt. to about70% wt., of the concentrate.

In addition to the polymers described in this invention, the dispersantformulations and the fluid formulations can further include one or moreadditional additives known to those skilled in the art. Such additivesinclude, for example, antioxidants, pour point depressants, detergents,dispersants, friction modifiers, anti-wear agents, VI improvers,anti-foam agents, corrosion and rust inhibitors, etc. Indeed, it isamong the advantages of the compositions of the invention that they areunusually efficient modifiers of dispersancy and/or viscometricproperties, such that in many cases significantly less of theseadditives need be added to achieve a desired combination of fluidproperties. For example, the Examples below show, inter alia, thatsignificant amounts of commercially available viscosity improvers can bedisplaced by adding a dispersant substance of the invention.

EXAMPLES

The following examples are intended to assist in a further understandingof the invention. The particular materials and conditions employed areintended to be further illustrative of the invention and are notlimiting upon the reasonable scope thereof.

In all of the following examples, the experimental polymerization andfunctionalization work was performed with dried reactors and equipmentand under strictly anaerobic conditions. Extreme care must be used toexclude air, moisture and other impurities capable of interfering withthe delicate chemical balance involved in the synthesis of the polymersof this invention, as will be apparent to those skilled in the art.

Example I Isoprene-Butadiene-Isoprene Triblock Copolymer

Three hundred milliliters (mL) of purified, dried cyclohexane wasintroduced into a six-hundred milliliter stirred glass reactor. Air wasremoved from the reactor under vacuum and replaced by dry nitrogen. Thereactor was equipped with an air driven stirrer, a pressure gauge,thermocouple, top face inlet valve, dip tube feeder with valve, heatingmantle and variable controller and combination nitrogen-vacuum inletwith valve. Three milliliters of a 0.1M solution of dipyridyl incyclohexane, 7.3 mL (90 mmol) of tetrahydrofuran freshly distilled frombenzophenone ketyl, and 1.8 mL (18 mmol) of purified isoprene wereinjected into the reactor. The temperature of the reactor and itscontents was raised to 50° C. The solution was then titrated by theaddition of 1.6M butyllithium until a persistent red color was obtained.Following this, 3.75 mL of 1.6M butyllithium was injected into thereactor in order to initiate polymerization of the isoprene. Thereaction was allowed to run for one hour, after which 47.5 g of purifiedbutadiene was pressured into the reactor at a rate such that thereaction temperature did not exceed 70° C. After one hour, the reactorpressure had returned to its initial level and the formation of thesecond block of the copolymer was completed. Isoprene (1.8 mL, 18 mmol)was again injected into the reaction to allow the formation of the thirdand final block of the triblock polymer. After one hour, 0.35 mL ofacetic acid (4.5 mmol) was injected into the reactor to quench thetriblock living anion. The color of the reaction mixture changed from adark amber to colorless immediately. The mixture was cooled to roomtemperature and filtered through alumina/Celite. An anti-oxidant Irganox1076 from Ciba-Geigy (100 ppm based on dry polymer) was added andsolvent was removed under reduced pressure to yield a triblock polymerof about 8400 molecular weight as a clear, colorless, viscous fluid.Infrared analysis (FTIR) showed the butadiene center block to possess55% 1,2- and 45% 1,4-microstructure.

Example II Viscosity as a Function of Molecular Weight

This example illustrates the relationship between the molecular weightof the triblock polymers prepared in the manner substantially the sameas that of Example I and their resulting bulk viscosities.

As is apparent from the data of FIG. 1, a linear relationship existsbetween the molecular weight of the unhydrogenatedisoprene-butadiene-isoprene polymers prepared as in Example I and thelog of their room temperature bulk viscosities as measured using aBrookfield Engineering LVT viscometer operating at, for example, 0.6 rpmwith spindle number 5.

Example III Hydrogenation of Isoprene-Butadiene-Isoprene TriblockCopolymer

A solution of 250 mL of cyclohexane and 23 g of a triblock polymerprepared in a manner similar to that described in Example I was purgedof air by evacuation followed by introduction of dry nitrogen. Thisamount of polymer contained 0.403 moles of polybutadiene unsaturation.To the polymer solution was added 25 mL of a hydrogenation catalystsolution comprised of triethylaluminum and nickel octoate in a 3.6:1ratio, with a nickel concentration of 0.1M in cyclohexane. The resultingmixture was placed in a Parr hydrogenation apparatus and pressured to 50psig hydrogen. The apparatus was vented and the process repeated twicemore, after which time the pressure was maintained at 50 psig ofhydrogen. The temperature was raised to 50° C. and the mixture wasagitated vigorously. Hydrogen was fed on demand in order to maintain 50psig in the vessel, and the flow rate was monitored by means of a flowmeter. The progress of the hydrogenation process was monitored both byinfrared spectroscopy (FTIR) and hydrogen flow rate. An IR spectrumobtained at the start of the process displayed the presence of primarilythe butadiene unsaturation (peaks at 995, 968, 910 cm⁻¹). After 30minutes, butadiene vinyl unsaturation (peaks at 995, 910 cm⁻¹) was gone,the trans-1,4-butadiene was significantly reduced (968 cm⁻¹) and theisoprene unsaturation remained. This final point corresponds to zerohydrogen flow. Upon completion of the selective hydrogenation process,the vessel was vented and the black reaction mixture was stirred in airwith ammonium hydroxide and methanol stoichiometrically equivalent tothe total catalyst metal content (11.5 mmol, 0.7 mL concentrated ammoniaand 0.5 mL methanol). Within several hours, the mixture had changed to adark green color indicative of oxidized nickel. The mixture was filteredthrough alumina/Celite, and an anti-oxidant was added in the amountequivalent to 100 ppm based on the dry polymer weight. Solvent was thenremoved under reduced pressure to yield the product as a clear,colorless, viscous fluid.

Example IV Viscosity as a Function of Molecular Weight of HydrogenatedTriblock Polymer

This example illustrates the relationship between the molecular weightof the selectively hydrogenated triblock polymers prepared in the mannerof Example III and their resulting bulk viscosities.

As is apparent in FIG. 2, a monotonic increase in room temperature bulkviscosity is observed as the molecular weight of the selectivelyhydrogenated triblock polymers is increased. In all cases, a BrookfieldEngineering LVT viscometer operating at, for example 0.6 rpm withspindle number 5, was used. Surprisingly, however, even at a molecularweight of ten thousand g/mol (Mn=Mw), the bulk viscosity does not exceedone million centipoises.

Example V Isoprene-Butadiene Random Copolymer

Eleven hundred milliliters of purified pentane was introduced under anitrogen atmosphere into a two quart glass-bowled pressure reactor. Thereactor was equipped with an air driven stirrer, a pressure gauge, athermometer well, a heat exchange coil, a top surface inlet valve, a diptube feeder with a valve, a syringe injection port containing a Vitonrubber gasket, and a blow-out disk (200 psi). Five milliliters of a 0.1Mdipyridyl in cyclohexane solution was injected into the reactor alongwith 8.0 mL of anhydrous tetrahydrofuran. Isoprene (9.3 g, 13.7 mL,0.136 mol), freshly distilled from sodium, was added via syringe to a300 mL Hoke bomb. Butadiene (124.0 g, 200 mL, 2.29 mol) was thenpressured into the same bomb. The bomb was fitted on top of the reactorand approximately half of the contents was pressured into it. Thesolution was heated to 40° C. and titrated by slow addition of 1.6Mn-butyllithium until an orangish color persisted. Then 4.2 mL (6.7 mmol)of n-butyllithium, was added. After several minutes, the remainder ofthe isoprene-butadiene solution was added. The temperature slowlyexothermed to 50° C. and was maintained at 50°-51° C. for 3 hours. Theliving anion was then quenched by the addition of 0.46 mL (3.7 mmol) of4-hydroxy-4-methyl-2-pentanone. An anti-oxidant Irganox 1076 fromCiba-Geigy (100 ppm based on dry polymer) was added and solvent wasremoved under reduced pressure from a small portion to yield a triblockpolymer of about 20,000 molecular weight as a clear, colorless, viscousfluid. Infrared analysis (FTIR) showed the butadiene center block topossess 55% 1,2- and 45% 1,4-microstructure.

Example VI Hydrogenation of Isoprene-Butadiene Random Copolymer

Part of the polymeric solution (195 g) described in Example V wasintroduced into a 0.5 L Fischer-Porter reactor. The total amount ofpolymer added to the reactor was 31.4 g which represents 0.540 moles ofbutadiene unsaturation. The hydrogenation catalyst was prepared byadding 35.1 mL of a 1.7M triethylaluminum solution (59.6 mmol) to asolution of 19.9 mmol of cobalt octoate in 153.0 mL (119.2 g) ofcyclohexane. The final catalyst solution was 0.1M in cobalt and had analuminum-cobalt ratio of 3:1. A portion of this catalyst (5.0 mL, 0.50mmol Co) was syringed into the reactor which had been purged/ventedthree times with nitrogen, then hydrogen, and pressured to 55 psig withhydrogen. The reaction exothermed to 34° C. and was maintained at30°-35° C. The progress of the hydrogenation was monitored by infrared(FTIR) analysis of hourly samples. After 4 hours an additional 4 mL(0.40 mmol) of catalyst was added. The reaction was terminated after6.25 h, when the IR showed minimal trans unsaturation (968 cm⁻¹) andcomplete disappearance of vinyl (910, 990 cm⁻¹). The catalyst was thenremoved by washing the polymer in the same type of reactor described inExample I with 300 mL of a 0.5M citric acid aqueous isopropanol (2:1water-IPA) solution. The mixture was vigorously mixed at 70° C. for 20minutes and allowed to settle. The pink aqueous layer was removed andthe entire wash step was repeated using an aqueous isopropanol (2:1water-IPA) solution. After addition of 0.2 g of Irganox 1076, thepolymer was isolated by removing the volatiles under reduced pressure.Gel permeation chromatography of a sample revealed little change in thepolydispersity index of the polymer had occurred as a result ofhydrogenation.

Example VII Isoprene-Butadiene Diblock Copolymer

Eleven hundred milliliters of purified pentane was introduced under anitrogen atmosphere into a two quart glass-bowled pressure reactor. Thereactor was equipped with an air driven stirrer, a pressure gauge, athermometer well, a heat exchange coil, a top surface inlet valve, a diptube feeder with a valve, a syringe injection port containing a Vitonrubber gasket, and a blow-out disk (200 psi). Five milliliters of a 0.1Mdipyridyl in cyclohexane solution was injected into the reactor alongwith 8.0 mL of anhydrous tetrahydrofuran. Isoprene (18.6 g, 27.3 mL,0.344 mol), freshly distilled from sodium, was added via syringe to thereaction vessel. The solution was heated to 50° C. and titrated by slowaddition of 1.6M n-butyllithium until an orangish color persisted. Then4.2 mL (6.7 mmol) of n-butyllithium was added. After 4 hr, butadiene(114.7 g, 155 mL, 2.12 mol) was pressured into the same reactor. Thesolution temperature was maintained at 50°-51° C. for 3 hours. Theremainder of the procedure was the same as that described in Example V.

Example VIII Hydrogenation of Isoprene-Butadiene Diblock Copolymer

The material described in Example VII was hydrogenated in the samemanner as Example VI using 23.3 mL of a 0.1M cobalt-aluminum catalyst(3:1Al/Co).

Example IX Addition of Maleic Anhydride to Selectively HydrogenatedIsoprene-Butadiene-Isoprene Triblock

A 500 milliliter three-neck round bottom flask fitted with a condenser,nitrogen inlet valve and overhead stirrer was charged with 94.6 g (9.46mmol) of triblock polymer prepared in much the same manner as wasdescribed in Examples I and III. The triblock had a molecular weight of10,000. Polyalphaolefin (4 cSt, 100 g) was added and the mixture wasstirred and heated to 150° C. under an inert atmosphere. Maleicanhydride (5.10 g, 52.1 mmol, ¹⁸ 6 equiv) was added to the hot mixture.The reactants were then stirred at 240° C. for 7 hours. After this time,the reaction was sparged with nitrogen at 200° C. for a half hour toremove any unreacted maleic anhydride. The reaction mixture was purifiedfurther for analysis by dissolving 10 g in 50 mL of cyclohexane andadding 60 mL of methanol slowly until the polymer/PAO mixture fell outof solution. An FTIR of the resulting material showed the characteristicanhydride bands at 1820 and 1788 cm⁻¹. A Total Acid Number (TAN)analysis revealed that 4.0 anhydride groups had been added to thepolymer chain.

Example X Imidization of Maleated IBI Triblock Polymer

A 3-neck 100 mL round bottom flask fitted with an overhead stirrer,nitrogen inlet valve, and a Dean-Stark trap was charged with 51.81 g ofmaleated IBI triblock prepared in Example VII. This material was 50%active in 4 cSt PAO. The mixture was heated to 130° C. and 1.5 mL (1.5g, 10.4 mmol) of aminopropylmorpholine was added. The temperature of thereaction was increased to 150° C. for 2 hours. FTIR showed that theanhydride bands had disappeared and were replaced by a strong band at1708 cm⁻¹. The reaction was then heated under high vacuum for 2 hours toremove the water and unreacted amine. The resulting material waspurified no further. Nitrogen content was found to be 0.44% (calc'd:0.51%).

Example XI Dispersancy Testing

Three dispersants of the invention, Dispersants A-C, were preparedsimilarly to the dispersants described in Examples I-X. Dispersants A-Cwere evaluated by spot dispersancy test (SDT), a traditional bench testfor measuring the performance of dispersants. These dispersants werecompared with two commercially available succinimide-modifiedpolyisobutene dispersants, denoted as Commercial Dispersants CD1 andCD2, respectively. FIG. 3 shows the performance of the three dispersantsof the invention at various treat rates, contrasted with that of thecommercial products. Percent dispersancy is shown on the ordinate, withthe larger values corresponding to better dispersancy properties. Thematerials of the invention are clearly superior to the commercialdispersants, exhibiting better dispersancy at equivalent treat rates. Inparticular, at low treat rates of 1.0%, each of the three compounds ofthe invention produced dispersancy which was twice as high as either ofthe commercial dispersants.

Example XII Viscometric Testing

Viscometric properties of materials prepared in accordance with ExamplesI-X were measured using a conventional method. Table 1 shows thatDispersant B at 6.3% in a 100 Neutral (100N) mineral oil stock produceda viscosity of 10.3 cSt, while 27.1% of commercial dispersant CD1 wasrequired to yield only 10.2 cSt, and 7.1% of commercial dispersant CD2yielded only 9.8 cSt. Clearly, the dispersant properties of these newmaterials are superior to those of the commercial products, sincesignificantly less dispersant was required to obtain equivalent orbetter viscosity. Viscosity index (VI) is also clearly improved, as isrelative thickening power (RTP), by the additives of the invention.

                  TABLE 1                                                         ______________________________________                                        VISCOMETRIC COMPARISON OF DISPERSANTS                                         IN 100N MINERAL OIL                                                           DISPERSANT                                                                              % IN STOCK  100° C. KV                                                                        VI    RTP                                    ______________________________________                                        CD1       27.1        10.2       135   1.1                                    CD2       7.1         9.8        142   3.9                                    Dispersant B                                                                            6.3         10.3       153   4.6                                    ______________________________________                                    

Example XIII Para-Methylstyrene-1,3-Butadiene Random Copolymer

One thousand milliliters of purified pentane and 100 mL oftetrahydrofuran distilled over benzophenone ketyl were introduced undera nitrogen atmosphere into a two quart glass bowled stirred pressurereactor. The reactor was equipped with an air driven stirrer, a pressuregauge, a thermometer well, a heat exchange coil, a top surface inletvalve, a dip tube feeder with a valve, a syringe injection portcontaining a Viton rubber gasket, and a blow-out disk (200 psi). Onemilliliter of a 0.1M dipyridyl in cyclohexane solution was injected intothe reactor along with 33.4 mL (30.0 g, 0.254 mol) of p-methylstyrene(p-MS) that had been passed through alumina. Butadiene (120 g, 2.22 mol)was then pressured into a 300 mL Hoke bomb. The bomb was fitted onto thereactor and the contents were pressured into it. The solution was heatedto 35° C. then titrated by slow addition of 1.6M n-butyllithium until ared color persisted. The catalyst, 4.7 mL of n-butyllithium, was added.Polymerization of the butadiene and p-MS was continued at 25°-30° C. for3.6 hours. The living anion was then quenched by the addition of 0.5 mLof 4-hydroxy-4-methyl-2-pentanone. A portion of the polymer wasconcentrated under reduced pressure. Gel permeation chromatography ofthe sample showed the polymer to have a number average molecular weight(Mn) and a weight average molecular weight (Mw) of 2.00×10⁴ and2.10×10⁴, respectively, and a polydispersity index of 1.05.

Example XIV Hydrogenation of p-Methylstyrene-1,3-Butadiene RandomCopolymer

The polymeric solution prepared in Example XIII was introduced into a 1LFischer-Porter reactor. The total amount of polymer added to the reactorwas 140 g, which represents 2.07 moles of butadiene unsaturation. Thehydrogenation catalyst was prepared by adding 121.5 mL of a 1.7Mtriethylaluminum solution (210 mmol) to a solution of 60.0 mmol ofcobalt octoate in 450 mL of cyclohexane. The final catalyst solution was0.1M in cobalt and had an aluminum-cobalt ratio of 3.5:1. A portion ofthis catalyst (50 mL, 5.00 mmol Co) was cannulaed into the reactor whichwas then purged four times with hydrogen gas and pressured to 55 psig.The reaction temperature exothermed to 50° C. and was immediately cooledto 30° C. with an ice bath. The progress of the hydrogenation wasmonitored by infrared (IR) analysis of hourly samples. The reaction wasterminated when the IR showed no existing olefin unsaturation. Thecatalyst was then removed by washing the polymer with 1L of a 0.5 Mcitric acid aqueous isopropanol (2:1 water-IPA) solution in the sametype of reactor described in Example XIII. The mixture was vigorouslystirred at room temperature for 15 minutes and then allowed to settle.The pink aqueous layer was removed. Another liter of citric acidsolution was added and the procedure was repeated. After the addition of0.5 g of antioxidant Irganox 1076, the polymer was concentrated underreduced pressure. Gel permeation chromatography revealed a Mn of2.31×10⁴, a Mw of 2.5×10⁴, and a polydispersity index of 1.10.

Example XV Bromination of the Hydrogenated p-Methylstyrene-1,3-ButadieneCopolymer

To a stirring solution of 54.4 g (2.59 mmol) of the hydrogenatedp-methylstyrene-butadiene copolymer described in Example XIV in 300 mLof cyclohexane under a nitrogen blanket was added 2.65 mL (8.28 g,0.0517 mol) of bromine via syringe. After the addition was complete, auv lamp (100 watt longwave mercury spot lamp) was shined directly on thereaction until the red bromine color disappeared (.sup.˜ 15-20 min). Thereaction mixture was concentrated under reduced pressure.

Example XVI Amination of the Brominated Hydrogenatedp-Methylstyrene-1,3-Butadiene Copolymer

To 10.0 g of a brominated p-methylstyrene-butadiene copolymer that was20 weight % p-MS was added 10.0 g of 4 cSt polyalphaolefin (PAO), 1.87 gof calcium oxide, and 3.7 mL (3.6 g, 0.0251 mol) ofN-aminopropylmorpholine. The reaction was stirred and heated undernitrogen at 150° C. for 18 hours, sparged with nitrogen for one hour at150° C., then hot filtered through a bed of Celite 545 (diatomateousearth).

Example XVII Dispersancy Testing

The aminated copolymer of Example XVI (Dispersant F) and two othersimilarly prepared dispersants of the invention (Dispersants D and E),were evaluated by SDT and compared with commercial dispersants CD1 andCD2 described previously. FIG. 4 shows the performance of these threedispersants at various treat rates, contrasted with that of thecommercial products. The materials of the invention are clearly superiorto the commercial dispersants, exhibiting better dispersancy atequivalent treat rates. Indeed, Dispersant F showed an SDT value of 100%at 1% treat rate.

Example XVIII Viscometric Testing

Viscometric properties of materials prepared in accordance with ExamplesXIII-XVI were measured using a conventional method. Table 2 shows thatDispersant E at 4.7% in a 100N mineral oil stock produced a viscosity of10.5 cSt, while 27.1% of Commercial dispersant CD1 was required to yield10.2 cSt, and 7.1% of commercial dispersant CD2 yielded only 9.8 cSt.Clearly, the viscosity improving properties of these new materials aresuperior to those of the commercial products, since significantly lessdispersant was required to obtain equivalent or better viscosity.

                  TABLE 2                                                         ______________________________________                                        DISPERSANT VISCOMETRICS IN 100N STOCK                                         DISPERSANT*                                                                              % IN STOCK OIL                                                                              KV (cSt)  VI   RTP                                   ______________________________________                                        CD1        27.1          10.2      135  1.1                                   CD2        7.1           9.8       142  3.9                                   Dispersant E                                                                             4.7           10.5      169  6.3                                   ______________________________________                                         *Dispersants are all 50% active in PAO.                                  

Table 3 compares Dispersant E with commercial products illustrating thecapacity of the dispersants of the invention to minimize the amount of acommercial viscosity improver required to improve in viscosity from 4cSt (i.e., no additives in the 100N stock) to 10 cSt.

                  TABLE 3                                                         ______________________________________                                        REPLACING VI IMPROVER WITH                                                    DISPERSANT IN 100N STOCK                                                              VISCOSITY  %            %                                                     (4% IN     COMMERCIAL   COMMERCIAL                                    DISPER- STOCK      VI IMPROVER  VI IMPROVER                                   SANT    OIL)       NEEDED       DISPLACED                                     ______________________________________                                        NONE    4.00       1.15         0                                             CD1     4.61       1.02         11                                            CD2     6.63       0.61         47                                            Disper- 8.23       0.18         85                                            sant E                                                                        ______________________________________                                    

Given an identical amount (4%) of each of the dispersants in the 100Neutral stock, Dispersant E of the invention increased viscosity to 8.23cSt while the commercial dispersants increased viscosity to only 4.61cSt and 6.63 cSt. To increase the viscosity of the 100N stock to 10 cSt,1.15% of a commercially available block copolymer viscosity improver wasrequired. Dispersant E in the stock reduced the required amount of to0.18%, a reduction of 85%. The commercial dispersants reduced the amountof required VI improver by only 11% and 47%.

Table 4 shows additional results for Dispersant E. In this case, thetargeted viscosity improvement was to 14 cSt from 4 cSt.

                  TABLE 4                                                         ______________________________________                                        REPLACING VI IMPROVER WITH                                                    DISPERSANT IN 100N STOCK                                                              VISCOSITY  %            %                                                     (4% IN     COMMERCIAL   COMMERCIAL                                    DISPER- STOCK      VI IMPROVER  VI IMPROVER                                   SANT    OIL)       NEEDED       DISPLACED                                     ______________________________________                                        NONE    4.00       1.58         0                                             CD1     4.61       1.46         8                                             CD2     6.63       1.00         37                                            Disper- 9.00       0.74         53                                            sant E                                                                        ______________________________________                                    

Here, 4% added Dispersant E provided viscosity of 9 cSt, while identicalamounts of the commercial dispersants produced viscosities of only 4.61cSt and 6.63 cSt. To raise the viscosity of the stock to 14 cSt, 1.58%of the commercial block copolymer VI improver was required. Dispersant Ereduced the required amount of VI improver to 0.74%, a reduction of 53%.The commercial dispersants reduced the required amount of VI improver byno more than 37%.

Example XIX Liquid Polybutadiene

Eleven hundred milliliters of purified pentane was introduced under anitrogen atmosphere into a two quart glass-bowled pressure reactor. Thereactor was equipped with an air driven stirrer, a pressure gauge, athermometer well, a heat exchange coil, a top surface inlet valve, a diptube feeder with a valve, a syringe injection port containing a Vitonrubber gasket, and a blow-out disk (200 psi). Into the reactor wasinjected 1.5 mL of a 0.1M dipyridyl in cyclohexane solution along with10.0 mL of anhydrous tetrahydrofuran (distilled over sodium benzophenoneketyl). Butadiene (150.0 g, 2420 mL, 2.77 mol) was then pressured into300 mL Hoke bomb. The bomb was fitted on top of the reactor and theentire contents was pressured into it. The solution was heated to 50° C.and titrated by slow addition of 1.6M n-butyllithium until an orangishcolor persisted. The catalyst, 3.5 mL (5.6 mmol) of 1.6M n-butyllithium,was added. The temperature was maintained between 40°-50° C. for 2 hoursafter which time the living anion was quenched by the addition of 0.35mL (2.8 mmol) of 4-hydroxy-4-methyl-2-pentanone. An antioxidant Irganox1076 from Ciba-Geigy (100 ppm based on dry polymer) was added andsolvent was removed under reduced pressure from a small portion to yielda polymer of about 30,000 (Mw/Mn=1.05) molecular weight as a clear,colorless, viscous fluid. Infrared analysis (FTIR) showed the butadieneto possess 67% 1,2- and 33% 1,4-microstructure.

Example XX Partial Hydrogenation of Liquid Polybutadiene

The polymer solution from Example XIX (minus 200 g) was introduced intoa 1 L Fischer-Porter reaction vessel. The hydrogenation catalyst was acobalt-triethylaluminum complex dissolved in cyclohexane. The solutionwas 0.1M in cobalt with an aluminum cobalt ratio of 3.5:1. After thereactor had been purged and vented first with nitrogen then withhydrogen, 70.0 mL of catalyst (7 mmol Co) was added to the reactor viacanula. The reactor was then pressured to 55 psig with hydrogen. Thereaction exothermed immediately from 21° C. to 43° C. before it wascooled below 35° C. It was allowed to exotherm again to 50° C. before itwas again cooled to about 35° C. Periodic samples were analyzed byinfrared spectroscopy (FTIR). They showed the disappearance of vinyl(990, 910 cm⁻¹) and trans (967 cm⁻¹) unsaturation. After 1.5 hours, when3.3% residual trans unsaturation (21 double bonds) remained, thereaction was terminated. The catalyst was then removed by washing thepolymer in the same type of reactor described in Example XIX with 800 mLof a 0.5M citric acid aqueous isopropanol (2:1 water-IPA) solution. Themixture was vigorously mixed at 70° C. for 20 minutes and allowed tosettle. The pink aqueous layer was removed and the entire wash step wasrepeated using an aqueous isopropanol (2:1 water-IPA) solution. Afteraddition of 0.2 g of Irganox 1076, the polymer was isolated by removingthe volatiles under reduced pressure. Gel permeation chromatographyshowed little molecular weight change (Mn=34,600; Mw/Mn=1.15).

Example XXI Addition of Maleic Anhydride to Incompletely HydrogenatedPolybutadiene

A 500 milliliter three-neck round bottom flask fitted with a condenser,nitrogen inlet valve and overhead stirrer was charged with 41.83 g (1.2mmol) of hydrogenated polybutadiene prepared in Example XX. Thepolybutadiene had a molecular weight of 34,000. Polyalphaolefin (4 cSt,60.7 g) was added and the mixture was stirred and heated to 180° C.under an inert atmosphere. Maleic anhydride (2.34 g, 23.9 mmol, ¹⁸ 20equiv) was added to the hot mixture. The reactants were then stirred at240°-250° C. for 7.5 hours. After this time, the reaction was spargedwith nitrogen at 190° C. for one hour to remove any unreacted maleicanhydride. The reaction mixture was purified further for analysis bydissolving 10 g in 50 mL of cyclohexane and adding 60 mL of isopropanolslowly until the polymer/PAO mixture fell out of solution. An FTIR ofthe resulting material showed the characteristic anhydride bands at 1820and 1789 cm⁻¹. A Total Acid Number (TAN) analysis revealed that onaverage there were 13.2 anhydride groups per polymer chain.

Example XXII Imidization of Maleated Polybutadiene

A 3-neck 100 mL round bottom flask fitted with an overhead stirrer andnitrogen inlet valve was charged with 37.14 g of maleated hydrogenatedpolybutadiene, 50% active in 4cSt PAO, prepared in Example XXI. Themixture was heated to 130° C. and 1.0 mL (1.0 g, 7.0 mmol) ofaminopropylmorpholine was added. The temperature of the reaction wasincreased to 150° C. for 2 hours. FTIR showed that the anhydride bandshad disappeared and were replaced by a strong band at 1708 cm⁻¹. Thereaction was then heated under high vacuum for 3 hours to remove thewater and unreacted amine. The resulting material was purified nofurther. Nitrogen content was found to be 0.46% (calc'd: 0.49%).

Example XXIII Dispersancy Testing

The dispersant of Example XXII was evaluated by SDT. This dispersant,denoted Dispersant G, was compared with the commercial dispersants CD1and CD2 described previously. FIG. 5 shows the performance of DispersantG at various treat rates, contrasted with that of the commercialproducts. The material of the invention is clearly superior to thecommercial dispersants, exhibiting better dispersancy at equivalenttreat rates. In particular, at low treat rates of 1.0%, Dispersant Gproduced dispersancy which was over twice as high as either of thecommercial dispersants.

Example XXIV Viscometric Testing

Viscometric properties of Dispersant G were measured using aconventional method. Table 5 shows that Dispersant G at 5.4% in a 100neutral mineral oil stock produced a viscosity of 10.5 cSt, while 27.1%of commercial dispersant CD1 was required to yield only 10.2 cSt, and7.1% of commercial dispersant CD2 yielded only 9.8 cSt. Clearly, theviscosity improving properties of this new material is superior to thoseof the commercial products, since significantly less dispersant wasrequired to obtain equivalent or better viscosity.

                  TABLE 5                                                         ______________________________________                                        VISCOMETRIC COMPARISON OF                                                     DISPERSANTS IN 100N MINERAL OIL                                                                     100° C. KV                                       DISPERSANT                                                                              % IN STOCK  (cSt)      VI    RTP                                    ______________________________________                                        CD1       27.1        10.2       135   1.1                                    CD2       7.1         9.8        142   3.9                                    Dispersant G                                                                            5.4         10.5       162   5.6                                    ______________________________________                                    

Example XXV 90% Vinyl Polybutadiene Star

Two thousand milliliters of purified pentane was introduced under anitrogen atmosphere into a one gallon glass-bowled pressure reactor. Thereactor was equipped with a motorized stirrer, a pressure gauge, athermometer well, a heat exchange coil, a top surface inlet valve, a diptube feeder with a valve, a syringe injection port containing a Vitonrubber gasket, and a blow-out disk (200 psi). Two milliliters of a 0.1Mdipyridyl in cyclohexane solution was injected into the reactor alongwith 40.0 mL of anhydrous tetrahydrofuran. Butadiene (185.0 g, 3.42 mol)was then pressured into a 1000 mL Hoke bomb. The bomb was fitted on topof the reactor and the contents were pressured into it. The solution washeated to 50° C. and titrated by slow addition of 1.6M n-butyllithiumuntil an orangish color persisted. The contents of the reactor werecooled to 30° C. The catalyst, 2.4 mL (3.85 mmol) of n-butyllithium, wasadded. Polymerization of the butadiene was maintained at 18° C. for 3hours and then was allowed to drift back to room temperature (˜25° C.)over a 2 hour period. To the living anion was added 3.8 mL (26.8 mmol)of purified divinyl benzene. The reaction was warmed to 50° C. andstirred for 3 hours. The living anion was then quenched by the additionof 0.25 mL (2.0 mmol) of 4-hydroxy-4-methyl-2-pentanone. A portion ofthe polymer was isolated by flocculation in isopropanol containingIrganox 1076 and dried in a vacuum oven. Gel permeation chromatographyof the sample showed the polymer to have a number average molecularweight (Mn) and a weight average (Mw) of 742,915 and 800,020,respectively, and a polydispersity index (Mw/Mn) of 1.08. Infrared(FTIR) analysis showed the butadiene microstructure to have ˜90%1,2-microstructure.

Example XXVI Hydrogenation of 90% Vinyl Polybutadiene Star

Part of the polymeric solution (150 g) described in Example XXV wasintroduced into a 0.5 L Fischer-Porter reactor. The total amount ofpolymer added to the reactor was 18.8 g which represents 34.8 mol ofbutadiene unsaturation. Two hundred milliliters of pentane was added tofurther dilute the polymer. The hydrogenation catalyst was prepared byadding 35.1 mL of a 1.7M diethylaluminum ethoxide solution (59.6 mmol)to a solution of 19.7 mmol of cobalt octoate in 198.6 mL (119.2 g) ofcyclohexane. The final catalyst solution was 0.1M in cobalt and had analuminum-cobalt ratio of 3.5:1. A portion of this catalyst (6.0 mL, 0.60mmol Co) was syringed into the reactor which had been purged/ventedthree times with nitrogen, then hydrogen, and pressured to 55 psig withhydrogen. The progress of the hydrogenation was monitored by infrared(FTIR) analysis of half hour samples. An additional 3.0 mL (0.3 mmol Co)of catalyst was added after one hour. The reaction was terminated after22 h, when the IR showed only 0.18% residual trans or 25 trans doublebonds per star polymer molecule. The catalyst was then removed bywashing the polymer in a Waring blender with 500 mL of a 0.5M citricacid aqueous isopropanol (2:1 water-IPA) solution. The mixture wasvigorously mixed at 70° C. for 20 minutes and allowed to settle. Thepink aqueous layer was removed and the entire wash step was repeatedusing an aqueous isopropanol solution. After addition of 0.2 g ofIrganox 1076, the polymer was isolated by flocculation in isopropanolcontaining Irganox 1076 and dried in a vacuum oven. Gel permeationchromatography of the sample revealed that little change in thepolydispersity index of the polymer had occurred as a result ofhydrogenation.

Example XXVII

The selectively hydrogenated polymer of Example XXVI is chemicallymodified with maleic anhydride followed by aminopropylmorpholine asdescribed in Examples IX and X to provide a dispersant VI improver.

Thus, while there have been described what are presently believed to bethe preferred embodiments of the present invention, those skilled in theart will realize that other and further embodiments can be made withoutdeparting from the spirit of the invention, and it is intended toinclude all such further modifications and changes as come within thetrue scope of the claims set forth herein.

What is claimed is:
 1. A dispersant substance for modifying thedispersancy or viscometric properties of a fluid, comprising:a copolymerof a first conjugated diene and a second conjugated diene, wherein:saidfirst conjugated diene comprises at least one relatively moresubstituted conjugated diene having at least five carbon atoms and theformula: ##STR19## wherein R¹ -R⁶ are each hydrogen or a hydrocarbylgroup, provided that at least one of R¹ -R⁶ is a hydrocarbyl group,provided that after polymerization, the unsaturation of the polymerizedconjugated diene of formula (1) has the formula: ##STR20## whereinR^(I), R^(II), R^(III) and R^(IV) are each hydrogen or a hydrocarbylgroup, provided that either both R^(I) and R^(II) are hydrocarbyl groupsor both R^(III) and R^(IV) are hydrocarbyl groups; and said secondconjugated diene comprises at least one relatively less substitutedconjugated diene different from the first conjugated diene and having atleast four carbon atoms and the formula: ##STR21## wherein R⁷ -R¹² areeach hydrogen or a hydrocarbyl group, provided that afterpolymerization, the unsaturation of the polymerized conjugated diene offormula (3) has the formula: ##STR22## wherein R^(V), R^(VI), R^(VII)and R^(VIII) are each hydrogen or a hydrocarbyl group, provided that oneof R^(V) or R^(VI) is hydrogen, one of R^(VII) or R^(VIII) is hydrogen,and at least one of R^(V), R^(VI), R^(VII) and R^(VIII) is a hydrocarbylgroup; and wherein said copolymer has been functionalized by a methodcomprising:selectively hydrogenating said copolymer to provide aselectively hydrogenated copolymer; and functionalizing said selectivelyhydrogenated copolymer to provide a functionalized copolymer having atleast one polar functional group.
 2. The dispersant substance of claim1, wherein said first and second conjugated dienes are polymerized as ablock copolymer comprising at least two alternating blocks:

    (I).sub.x -(B).sub.y or (B).sub.y -(I).sub.x,

wherein: the block (I) comprises at least one polymerized conjugateddiene of formula (1); the block (B) comprises at least one polymerizedconjugated diene of formula (3); x is the number of polymerized monomerunits in block (I) and is at least 1, and y is the number of polymerizedmonomer units in block (B) and is at least
 25. 3. The dispersantsubstance of claim 1, wherein said first and second conjugated dienesare polymerized as a random copolymer.
 4. The dispersant substance ofclaim 1, wherein said first and second conjugated dienes are polymerizedas a branched or star-branched copolymer.
 5. The dispersant substance ofclaim 1, wherein said copolymer has a molecular weight of at least about2,000.
 6. The dispersant substance of claim 5, wherein said copolymerhas a molecular weight of from about 2,000 to about 1,000,000.
 7. Thedispersant substance of claim 6, wherein said copolymer has a molecularweight of from about 5,000 to about 500,000.
 8. The dispersant substanceof claim 1, wherein said first conjugated diene is included in saidpolymer in an amount of from about 0.5% wt. to about 35% wt.; and saidsecond conjugated diene is included in said polymer in an amount of fromabout 75% wt. to about 99.5% wt.
 9. The dispersant substance of claim 8,wherein said first conjugated diene is included in said polymer in anamount of from about 1% wt. to about 25% wt.; and said second conjugateddiene is included in said polymer in an amount of from about 75% wt. toabout 99% wt.
 10. The dispersant substance of claim 2, wherein x is fromabout 1 to about 600, and y is from 30 to 4,000.
 11. The dispersantsubstance of claim 10, wherein x is from about 1 to about 350, and y isfrom 30 to about 2,800.
 12. The dispersant substance of claim 1, whereinsaid selectively hydrogenating step provides a selectively hydrogenatedcopolymer wherein the unsaturation of formula (4) is substantiallycompletely hydrogenated to retain substantially none of the originalunsaturation, while unsaturation of formula (2) retains a sufficientamount of its original unsaturation to permit said functionalizing ofsaid copolymer.
 13. The dispersant substance of claim 12, wherein afterthe selectively hydrogenating step, the Iodine Number for residualunsaturation of formula (2) is from about 50% to about 100% of theIodine Number prior to the selectively hydrogenating step.
 14. Thedispersant substance of claim 13, wherein after the selectivelyhydrogenating step, the Iodine Number for residual unsaturation offormula (2) is about 100% of the Iodine Number prior to the selectivelyhydrogenating step.
 15. The dispersant substance of claim 12, whereinafter the selectively hydrogenating step, the Iodine Number for residualunsaturation of formula (4) is from about 0% to about 10% of the IodineNumber prior to the selectively hydrogenating step.
 16. The dispersantsubstance of claim 15, wherein after the selectively hydrogenating step,the Iodine Number for residual unsaturation of formula (4) is from about0% to about 0.5% of the Iodine Number prior to the selectivelyhydrogenating step.
 17. The dispersant substance of claim 16, whereinafter the selectively hydrogenating step, the Iodine Number for residualunsaturation of formula (4) is from about 0% to about 0.2% of the IodineNumber prior to the selectively hydrogenating step.
 18. The dispersantsubstance of claim 1, wherein the conjugated diene of formula (1)comprises isoprene, 2,3-dimethyl-butadiene, 2-methyl-1,3-pentadiene,myrcene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene,2-phenyl-1,3-butadiene, 2-phenyl-1,3-pentadiene, 3-phenyl-1,3pentadiene, 2,3-dimethyl-1,3-pentadiene, 2-hexyl-1,3-butadiene,3-methyl-1,3-hexadiene, 2-benzyl-1,3-butadiene, 2-p-tolyl-1,3-butadiene,or mixtures thereof.
 19. The dispersant substance of claim 18, whereinthe conjugated diene of formula (1) comprises isoprene, myrcene,2,3-dimethyl-butadiene, or 2-methyl-1,3-pentadiene.
 20. The dispersantsubstance of claim 19, wherein the conjugated diene of formula (1)comprises isoprene.
 21. The dispersant substance of claim 1, wherein theconjugated diene of formula (3) comprises 1,3-butadiene, 1,3-pentadiene,1,3-hexadiene, 1,3-heptadiene, 2,4-heptadiene, 1,3-octadiene,2,4-octadiene, 3,5-octadiene, 1,3-nonadiene, 2,4-nonadiene,3,5-nonadiene, 1,3-decadiene, 2,4-decadiene, 3,5-decadiene, or mixturesthereof.
 22. The dispersant substance of claim 21, wherein theconjugated diene of formula (3) comprises 1,3-butadiene, 1,3-pentadiene,or 1,3-hexadiene.
 23. The dispersant substance of claim 22, wherein theconjugated diene of formula (3) comprises 1,3-butadiene.
 24. Thedispersant substance of claim 2, wherein said conjugated diene offormula (3) comprises 1,3-butadiene, and each of the (B) blocks is amixture of 1,4- and 1,2-units.
 25. The dispersant substance of claim 24,wherein each of the (B) blocks has at least about 25% of the 1,2-units.26. The dispersant substance of claim 25, wherein each of the (B) blockshas from about 30% to about 90% of the 1,2-subunits.
 27. The dispersantsubstance of claim 26, wherein each of the (B) blocks has from about 45%to about 65% of the 1,2-units.
 28. The dispersant substance of claim 1,wherein said functionalizing step provides a functionalized polymerhaving at least one functional group selected from the group consistingof halogen groups, hydroxyl groups, epoxy groups, sulfonic acid groups,mercapto groups, carboxylic acid groups, and mixtures thereof.
 29. Thedispersant substance of claim 28, wherein said functional groupcomprises an unsaturated carboxylic acid derivative group selected fromthe group consisting of acrylic acid, maleic acid, fumaric acid, maleicanhydride, methacrylic acid, and the like.
 30. The dispersant substanceof claim 29, wherein said functional group comprises maleic anhydride.31. The dispersant substance of claim 28, wherein said functional groupis selected from the group consisting of halogen groups, epoxy groups,sulfonic acid groups, and carboxylic acid derivative groups, andfunctionalizing step further comprises modifying the functionalizedcopolymer by reaction with an amine, polyamine, or a combinationthereof.
 32. The dispersant substance of claim 1, wherein saidfunctionalizing step comprises:reacting said selectively hydrogenatedcopolymer with maleic anhydride to provide a maleated copolymer, andmodifying said maleated copolymer with an amine, a polyamine or acombination thereof.
 33. The dispersant substance of claim 1, whereinsaid polymer is distributed in a carrier fluid to provide a dispersantconcentrate.
 34. The dispersant substance of claim 33, wherein saidpolymer is included in an amount of from about 5% wt. to about 90% wt.of the dispersant concentrate.
 35. The dispersant substance of claim 34,wherein said polymer is included in an amount of from about 10% wt. toabout 70% wt. of the dispersant concentrate.
 36. The dispersantsubstance of claim 1, further comprising at least one additive selectedfrom the group consisting of antioxidants, pour point depressants,detergents, dispersants, friction modifiers, anti-wear agents, anti-foamagents, corrosion and rust inhibitors, viscosity index improvers, andthe like.
 37. A method of modifying the dispersancy or viscometricproperties of a fluid, comprising:admixing with a fluid an amount of adispersant substance sufficient to provide a dispersant-modified fluidhaving modified dispersant or viscometric properties; wherein saiddispersant substance comprises: a copolymer of a first conjugated dieneand a second conjugated diene, wherein:said first conjugated dienecomprises at least one relatively more substituted conjugated dienehaving at least five carbon atoms and the formula: ##STR23## wherein R¹-R⁶ are each hydrogen or a hydrocarbyl group, provided that at least oneof R¹ -R⁶ is a hydrocarbyl group, provided that after polymerization,the unsaturation of the polymerized conjugated diene of formula (1) hasthe formula: ##STR24## wherein R^(I), R^(II), R^(III) and R^(IV) areeach hydrogen or a hydrocarbyl group, provided that either both R^(I)and R^(II) are hydrocarbyl groups or both R^(III) and R^(IV) arehydrocarbyl groups; and said second conjugated diene comprises at leastone relatively less substituted conjugated diene different from thefirst conjugated diene and having at least four carbon atoms and theformula: ##STR25## wherein R⁷ -R¹² are each hydrogen or a hydrocarbylgroup, provided that after polymerization, the unsaturation of thepolymerized conjugated diene of formula (3) has the formula: ##STR26##wherein R^(V), R^(VI), R^(VII) and R^(VIII) are each hydrogen or ahydrocarbyl group, provided that one of R^(V) or R^(VI) is hydrogen, oneof R^(VII) or R^(VIII) is hydrogen, and at least one of R^(V), R^(VI),R^(VII) and R^(VIII) is a hydrocarbyl group; and wherein said copolymerhas been functionalized by a method comprising:selectively hydrogenatingsaid copolymer to provide a selectively hydrogenated copolymer; andfunctionalizing said selectively hydrogenated copolymer to provide afunctionalized copolymer having at least one polar functional group. 38.The method of claim 37, comprising admixing said dispersant substance inan amount of from about 0.001% wt. to about 20% wt. of saiddispersant-modified fluid.
 39. The method of claim 38, comprisingadmixing said dispersant substance in an amount of from about 0.1% wt.to about 10% wt. of said dispersant-modified fluid.
 40. The method ofclaim 39, comprising admixing said dispersant substance in an amount offrom about 0.5% wt. to about 5% wt. of said dispersant-modified fluid.41. The method of claim 37, wherein said fluid is selected from thegroup consisting of motor oils, transmission fluids, hydraulic fluids,gear oils, aviation oils, normally liquid fuels, and the like.
 42. Themethod of claim 37, further comprising admixing with said fluid at leastone additive selected from the group consisting of antioxidants, pourpoint depressants, detergents, dispersants, friction modifiers,anti-wear agents, anti-foam agents, corrosion and rust inhibitors,viscosity index improvers, and the like.
 43. A dispersant-modified fluidhaving modified dispersancy or viscometric properties comprising:afluid; and a dispersant substance comprising:a copolymer of a firstconjugated diene and a second conjugated diene, wherein: said firstconjugated diene comprises at least one relatively more substitutedconjugated diene having at least five carbon atoms and the formula:##STR27## wherein R¹ -R⁶ are each hydrogen or a hydrocarbyl group,provided that at least one of R¹ -R⁶ is a hydrocarbyl group, providedthat after polymerization, the unsaturation of the polymerizedconjugated diene of formula (1) has the formula: ##STR28## whereinR^(I), R^(II), R^(III) and R^(IV) are each hydrogen or a hydrocarbylgroup, provided that either both R^(I) and R^(II) are hydrocarbyl groupsor both R^(III) and R^(IV) are hydrocarbyl groups; and said secondconjugated diene comprises at least one relatively less substitutedconjugated diene different from the first conjugated diene and having atleast four carbon atoms and the formula: ##STR29## wherein R⁷ -R¹² areeach hydrogen or a hydrocarbyl group, provided that afterpolymerization, the unsaturation of the polymerized conjugated diene offormula (3) has the formula: ##STR30## wherein R^(V), R^(VI), R^(VII)and R^(VIII) are each hydrogen or a hydrocarbyl group, provided that oneof R^(V) or R^(VI) is hydrogen, one of R^(VII) or R^(VIII) is hydrogen,and at least one of R^(V), R^(VI), R^(VII) and R^(VIII) is a hydrocarbylgroup; and wherein said copolymer has been functionalized by a methodcomprising:selectively hydrogenating said copolymer to provide aselectively hydrogenated copolymer; and functionalizing said selectivelyhydrogenated copolymer to provide a functionalized copolymer having atleast one polar functional group.
 44. The dispersant-modified fluid ofclaim 43, wherein said dispersant substance is included in an amount offrom about 0.001% wt. to about 20% wt.
 45. The dispersant-modified fluidof claim 44, wherein said dispersant substance is included in an amountof from about 0.1% wt. to about 10% wt.
 46. The dispersant-modifiedfluid of claim 45, wherein said dispersant substance is included in anamount of from about 0.5% wt. to about 5% wt.
 47. Thedispersant-modified fluid of claim 46, wherein said fluid is selectedfrom the group consisting of motor oils, transmission fluids, hydraulicfluids, gear oils, aviation oils, normally liquid fuels, and the like.48. The dispersant-modified fluid of claim 43, wherein said lubricantfluid further comprises at least one additive selected from the groupconsisting of antioxidants, pour point depressants, detergents,dispersants, friction modifiers, anti-wear agents, anti-foam agents,corrosion and rust inhibitors, viscosity index improvers, and the like.49. A dispersant substance for modifying the dispersancy or viscometricproperties of a lubricant fluid, comprising:a homopolymer of aconjugated diene, wherein:said conjugated diene has at least five carbonatoms and the formula: ##STR31## wherein R¹ -R⁶ are each hydrogen or ahydrocarbyl group, provided that at least one of R¹ -R⁶ is a hydrocarbylgroup, provided that after polymerization, the unsaturation of thepolymerized conjugated diene of formula (1) has the formula: ##STR32##wherein R^(I), R^(II), R^(III) and R^(IV) are each hydrogen or ahydrocarbyl group, provided that either both R^(I) and R^(II) arehydrocarbyl groups or both R^(III) and R^(IV) are hydrocarbyl groups; orsaid conjugated diene has at least four carbon atoms and the formula:##STR33## wherein R⁷ -R¹² are each hydrogen or a hydrocarbyl group,provided that after polymerization, the unsaturation of the polymerizedconjugated diene of formula (3) has the formula: ##STR34## whereinR^(V), R^(VI), R^(VII) and R^(VIII) are each hydrogen or a hydrocarbylgroup, provided that one of R^(V) or R^(VI) is hydrogen, one of R^(VII)or R^(VIII) is hydrogen, and at least one of R^(V), R^(VI), R^(VII) andR^(VIII) is a hydrocarbyl group; wherein said polymer has beenfunctionalized by a method comprising:selectively hydrogenating saidpolymer to provide a selectively hydrogenated polymer; andfunctionalizing said selectively hydrogenated polymer to provide afunctionalized polymer having at least one polar functional group. 50.The dispersant substance of claim 49, wherein said functionalizing stepincludes modifying said selectively hydrogenated polymer to provide saidfunctionalized polymer having at least one functional group selectedfrom the group consisting of halogen groups, hydroxyl groups, epoxygroups, sulfonic acid groups, mercapto groups, carboxylic acidderivative groups, and mixtures thereof.
 51. The dispersant substance ofclaim 50, wherein said functionalizing step further comprises reactingsaid functionalized polymer with a monoamine, a polyamine, or acombination thereof.
 52. The dispersant substance of claim 49, whereinsaid polymer is distributed in a carrier fluid to provide a dispersantconcentrate.
 53. A method of modifying the dispersancy or viscometricproperties of a fluid, comprising:admixing with a fluid an amount of adispersant substance sufficient to provide a fluid having modifieddispersancy or viscometric properties; wherein said dispersant substancecomprises:a homopolymer of a conjugated diene, wherein: said conjugateddiene has at least five carbon atoms and the formula: ##STR35## whereinR¹ -R⁶ are each hydrogen or a hydrocarbyl group, provided that at leastone of R¹ -R⁶ is a hydrocarbyl group, provided that afterpolymerization, the unsaturation of the polymerized conjugated diene offormula (1) has the formula: ##STR36## wherein R^(I), R^(II), R^(III)and R^(IV) are each hydrogen or a hydrocarbyl group, provided thateither both R^(I) and R^(II) are hydrocarbyl groups or both R^(III) andR^(IV) are hydrocarbyl groups; or said conjugated diene has at leastfour carbon atoms and the formula: ##STR37## wherein R⁷ -R¹² are eachhydrogen or a hydrocarbyl group, provided that after polymerization, theunsaturation of the polymerized conjugated diene of formula (3) has theformula: ##STR38## wherein R^(V), R^(VI), R^(VII) and R^(VIII) are eachhydrogen or a hydrocarbyl group, provided that one of R^(V) or R^(VI) ishydrogen, one of R^(VII) or R^(VIII) is hydrogen, and at least one ofR^(V), R^(VI), R^(VII) and R^(VIII) is a hydrocarbyl group; wherein saidpolymer has been functionalized by a method comprising:selectivelyhydrogenating said polymer to provide a partially hydrogenated polymer;and functionalizing said partially hydrogenated polymer to provide afunctionalized polymer having at least one polar functional group.
 54. Adispersant-modified fluid having modified dispersancy or viscometricproperties, comprising:a fluid; and a dispersant substance comprising: ahomopolymer of a conjugated diene, wherein:said conjugated diene has atleast five carbon atoms and the formula: ##STR39## wherein R¹ -R⁶ areeach hydrogen or a hydrocarbyl group, provided that at least one of R¹-R⁶ is a hydrocarbyl group, provided that after polymerization, theunsaturation of the polymerized conjugated diene of formula (1) has theformula: ##STR40## wherein R^(I), R^(II), R^(III) and R^(IV) are eachhydrogen or a hydrocarbyl group, provided that either both R^(I) andR^(II) are hydrocarbyl groups or both R^(III) and R^(IV) are hydrocarbylgroups; or said conjugated diene has at least four carbon atoms and theformula: ##STR41## wherein R⁷ -R¹² are each hydrogen or a hydrocarbylgroup, provided that after polymerization, the unsaturation of thepolymerized conjugated diene of formula (3) has the formula: ##STR42##wherein R^(V), R^(VI), R^(VII) and R^(VIII) are each hydrogen or ahydrocarbyl group, provided that one of R^(V) or R^(VI) is hydrogen, oneof R^(VII) or R^(VIII) is hydrogen, and at least one of R^(V), R^(VI),R^(VII) and R^(VIII) is a hydrocarbyl group; wherein said polymer hasbeen functionalized by a method comprising:selectively hydrogenatingsaid polymer to provide a partially hydrogenated polymer; andfunctionalizing said partially hydrogenated polymer to provide afunctionalized polymer having at least one polar functional group.